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.
to buy bitcoin using bitcoin is likely to happen but you have to find a seller who can accept bitcoin for his payment method because currently there are few who accept bitcoin as a legitimate payment.
Only few people or real estate businesses use Bitcoin method because they are well awared of this digital currency. Soon you will be watching and observing that Bitcoin is using as payment system. After spreading it fully in Japan many other countries are adopting it fully but I think half of the world are still using fiat. They will soon realize it that using Bitcoin is in our benefit and will be using everywhere even buying small things.