Thats what your apple ID is for. The problem with ownership on the blockchain is it still depends on a central authority recognition for most useful things. For instance your home title still needs to be recognized by the government. And if thats the case you might as well just have a database derived from the authority.

Now if you wanted to change the whole system to where the government doesnt need authority over home titles anymore in any way (taxation, ownership enforcement, etc), then thats a possibility. Not saying this is a good or bad idea. Phones are harder for me to see this as ever a possibility because its really a partnership where Apple provides ongoing support.