Yes, the property market has benefited from the surprisingly good sale of the Tsuen Wan West station site. I think it would be all right to buy a bigger flat, subject to your financial situation. There is little chance that property prices will drop significantly because the new government has no intention of introducing measures to dampen the market, and interest rates should remain low for some time. However, there are not many three-bedroom flats on offer at Vision City, as demand is strong. I advise you to keep an eye on the flats when they become available for sale and then you can decide what offers to make.
The answer depends on factors such as the supply of new flats in the district, interest rates, and the economic outlook. I don't have a crystal ball to predict them all but regarding the supply of flats in Ma On Shan, there are some projects poised to be launched and their prices will not be low. Therefore, you may hold your property for a while before selling. However, if this is the only flat you have, I suggest you do not sell, because it will be difficult to find another flat with this price tag on the market.