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.
Your right we can buy a house with bitcoin. We just need a person have bitcoin wallet and contract of to sign between you and the owner of the house. Nothing is impossible if you want to do and in bitcoin nothing is impossible as long you have lot of bitcoin.