Bitcoin as collateral will not roll in traditional mortgages I would expect ever. Traditional mortgages use the house as collateral & nothing more. When they do allow Bitcoin in the equation (it hasn’t rolled yet) there’s 2 possible scenarios that it could be considered as. Income - which would be that you could consider a percentage of your holdings as monthly income & assets which you could use as reserves only. In both scenarios it will need to be in a wallet that has monthly statements & account numbers. It’s not going to be as exciting as it was made out to be.