Can you buy a house with BTC? Yes! All you need is a buyer with coins and a seller that will accept them. The value of the transaction is as of the date of the contract, when the coins change hands.
Yes bitcoin can buy a house if the seller accept the bitcoin. But I think it is still possible if you will sell your bitcoin and tuen it into a paper money. If you have a lot of bitcoin you can save it and have to will to buy a house.