The nightmare scenario: Russian President Boris Yeltsin, hospitalised with what is officially described as a respiratory virus, is eventually acknowledged to have died of a massive heart attack.
With no obvious successor in place, but no longer able to conduct its internal squabbles behind hermetically sealed doors as it did in the days of Soviet one-party rule, the Kremlin is in chaos.
No one is in control of the state, the army, the nuclear arsenal. Foreign capital flees. The economy implodes. Tanks roll in the streets. General Alexander Lebed, one-time Yeltsin ally, then his bitter enemy, has staged a military putsch backed by old-style communist Gennady Zyuganov and extreme-right demagogue Vladimir Zhirinovsky.
Together, this terrifying triumvirate sets about blocking all further market reforms, undoing economic and political liberalisation and re-imposing dictatorship and the machinery of oppression. Its stated aim, pursued with a militaristic efficiency, is the re-conquest of the old Soviet empire.
Six years ago, in the failed coup that toppled Mikhail Gorbachev and installed Mr Yeltsin in the Kremlin, the plotters at the centre of the turmoil believed something of the sort was still possible.
They were wrong then. The army did not back them, although the defence minister was one of the conspirators. In December 1997, they would not even be taken seriously.
That Mr Yeltsin's condition is graver than his doctors admit cannot be ruled out. Although his personal physician and the cardiac specialists who rescued him from his deathbed last year all say his condition is not life-threatening and is unrelated to his previous heart ailments, this may be a smokescreen. Already, his spokesman has been forced to deny radio reports of a severe brain spasm. Previous heart attacks have also been described as colds. The old Kremlin habits die hard.
Even if it is a cold, a severe respiratory infection in a man of 66 with a history of severe health problems can easily become critical.
But if Mr Yeltsin were to die tomorrow, Russians expect the army to stay in its barracks. Unpaid, demoralised and weakened by years of neglect and deliberately brought to heel after the disastrous war against the Chechen rebels, it is in no condition to dictate to the politicians.
And as Michael Share, lecturer in European and Russian history at the University of Hong Kong, pointed out, the army has no Latin-American or Asian-style tradition of staging coups.
'Not since the 18th century has the army intervened in government affairs,' he said.
Meanwhile, although it suits Mr Yeltsin to keep the power firmly in his own hands, the limited institutional framework he has allowed to develop should be strong enough to prevent immediate chaos. There need be no repeat of the paralysis that used to grip the Soviet Union during an interregnum.
The constitution provides for the Prime Minister, Viktor Chernomyrdin, to take over the reins of government automatically should the President die or become incapacitated. He then has three months to call new presidential elections.
Whether any of the likely candidates has anything like either the political stature or the extraordinary survival skills of a Boris Yeltsin is another matter.
Of more interest is how the bitter personal rivalries within Mr Yeltsin's Government and among the big business 'oligarchs' who pull the strings from outside will play themselves out if Mr Yeltsin's illness leaves him weakened but still nominally in charge.
Mr Yeltsin's rule has been marked less by good or consistent government than by intrigue and power-politics. A past master of the old Soviet arts of playing his enemies against each other and of elevating favourites to high positions only to knock them down, he has steered a course between factions rather than come down firmly on the side of economic reform.
The latest bout of skulduggery gives some idea of just how Mr Yeltsin has operated.
Leading economic reformer Anatoly Chubais lost his job as finance minister over claims of corruption involving an advance of $690,000 for a book. Three other reformers and co-authors accepted similar sums and lost their jobs too.
With them went fellow reformer and the Government's most popular politician, Boris Nemtsov, who lost his job at the Energy Ministry even though he was untainted by the scandal.
Yet both Mr Chubais and Mr Nemtsov retained their posts as deputy prime ministers. Some analysts said Mr Nemtsov was only fired to limit the damage to Mr Chubais.
But Mr Chernomyrdin, whose love-hate relationship with Mr Chubais has been the subject of newspaper commentaries, seems to be the only man smiling at seeing his deputies brought down a peg.
The only one, that is, apart from the big businessmen who had fallen out with the two reformers for failing to award them the big contracts they had come to expect from their previously cosy relationship with the Yeltsin administration. By some accounts, they had recently fallen in with Mr Chernomyrdin.
Behind his hand, perhaps Mr Yeltsin was also smiling. Replacing Mr Chubais as Finance Minister was Mikhail Zadornov, who defected from rival reformer Grigory Yavlinsky's Yabloko party. Mr Yavlinsky is furious.
And Mr Nemtsov will have to watch his back. The new man, popular and without the Deputy Prime Minister's political baggage, could be the man to replace him in Mr Yeltsin's affections from now on.
As one Russian observer puts it: 'This skill in manipulation may be Yeltsin's best feature. Otherwise he couldn't survive. But nobody knows if it is good for the country.
'It gives a certain stability, but nobody knows what will happen next.' Could anybody perform the same kind of balancing act with Mr Yeltsin incapacitated or, like Leonid Brezhnev, in power but no longer in control of his faculties? 'Maybe no one in Russia is equal to Mr Yeltsin now,' the Russian observer said.
At least if Mr Chernomyrdin did go to the country there would be a greater pool of candidates for the succession.
According to Mr Share, the line-up of possible presidential hopefuls might start with Mr Nemtsov. At 38, he is one of only two likely candidates the world may recognise as a Western-style democrat. (The other is Mr Yavlinsky, a minor player.) With a 40 per cent rating in the polls, Mr Share says, the former governor of Nizhny-Novgorod is certainly the most popular candidate and Mr Yeltsin's current favourite.
But other reports suggest Mr Yeltsin's own unpopularity, plus the fall-out from the Chubais scandal, may undermine Mr Nemtsov.
The Kommersant Daily recently said 'his playboy image' was not enough to win him the support of the masses. Two of Russia's three main television channels, owned by Mr Nemtsov's businessman enemies, have ignored him in recent weeks. Their candidate as heir apparent to the presidency: the grey but cunning political survivor from the Soviet era, Mr Chernomyrdin.
'The party of power', as the faction supporting the President is known, is unlikely to want both men to run against each other.
Number two on Mr Share's list would be Mr Zyuganov, leader of the Communist Party. Still trying to garner support from the elderly and the millions of losers from the demise of the old socialist system, he has a strong support base among those the regime has been unable to find it in its budget to pay. Yet his following is dwindling and the party has split into many factions. Mr Zyuganov's image was badly damaged recently when cold feet about the possibility of parliamentary elections pushed him into compromise with the Government, instead of a threatened vote of no confidence. 'His image as a battler for the people has gone,' the Russian observer said.
Waiting in the wings is the mayor of Moscow, the popular Yury Luzhkov, although he has consistently said he will not run for the presidency. Handicapped by his exclusively Moscow base, he has recently been trying to build an image outside the capital at least at the level of the provincial leaders he has regularly invited to take part in conferences and meetings, and with whom he has been ready to share foreign investment capital.
In the run-up to Moscow's local parliamentary elections today, Mr Luzhkov has tried to stay out of the big national debate between Communists and Democrats and ruled the city like a fiefdom. Loyalty to Mr Yeltsin is vital. The last thing he needs is a burdensome local alignment.
The Moscow News recently tipped him to take over from Mr Chernomyrdin as premier, should Mr Yeltsin need to sack his Government following a vote of no confidence.
Meanwhile, Mr Nemtsov has described Mr Luzhkov as a kind of bureaucrat capitalist, at the other extreme from the 'oligarchs' who believes 'all power, all property and money shall belong to civil servants'.
General Lebed and Mr Zhirinovsky would also run again, although neither has a serious chance, except in coalition.
Yet unless the President's situation deteriorates suddenly, the matter is academic. None of the contenders will have a shot at the presidency until this term ends in 2000.
By then, Mr Yeltsin's particular brand of political puppeteering may well have altered the line-up beyond recognition.