[Someone]

What fraction of the market will use over 64GB? I'm guessing it is only a tiny fraction.

Ignoring that, let's assume there is a significant market there. What fraction of that market would be able to move their data from their old phone to their new phone? Again, I would guess a tiny fraction. Syncing 512GB in a reasonable time frame would likely require a direct computer connection at USB 3 speed or thereabouts.

So, your best bet likely is a phone that allows plugging in a 512 GB flash module.

[canow]

I would be using the phone as a backup of my main data and I don't care how long it takes to first transfer it because it would be fast to transfer the data changes using wifi-ac afterwards