The math seems OK to me, but someone arguing in favor of hyperbitcoinization might (1) argue against 'only' assuming 5x (2) wonder whether looking at a relatively short 10-year period makes sense (3) wonder whether the house will really 'stay the same' if we hyperbitcoinize (sweet word 🤩) or whether houses might go down in fiat terms while BTC goes up (4) related to point 3: wonder whether you will still be able to buy a house with a 100% mortgage and no down payment after we hyperbitcoinize. And the tax / freedom / privacy stuff already mentioned by others.
Discussion
1) 5x is a lot, in a deflationary environment. You could assume more, but then you'd need fiat inflation, which might cause the house price to also rise.
2) Anything over 10 years is complete guessing.
3) Houses will continue to be scarce until the house-owning population declines (i.e. Boomers) and frees up real estate.
4) After hyperbitcoinization, most mortgages don't really make sense. At most, maybe rent-to-own plans.
If you say so - food for thought 💪