How will mortgages work in a bitcoin world?

Buying a house is generally a good investment because even without any appreciation on the value of the house, the cost of the mortgage payment will become less (over 30 years in the US) as inflation eats away at the value of the dollar or other fiat currencies. Using round numbers a $500 dollar monthly mortgage payment with 5% inflation will be the same as $107 payment in 30 years.

But if the world moves to bitcoin and the value of bitcoin is always rising the cost of that mortgage payment will be constantly going up. So to purchase a house the value needs to be constantly going up at a rate that exceeds the increased value in bitcoin.

Won't the interest rates that banks need to be worth the risk be insanely high to the point no one will be able to get a mortgage?