The ones from the SSD yes, they are just memories and the controller is somewhere on its motherboard...
I'm thinking we can only go to around 128GB because I can't see any 256 one with the same pinout.
Doesn't mean is that later someone could actually start selling a different memory with its own board that could still be compatible with switch from their different board design, I don't know how much would it change in the pineouts from the switch emmc board connector to something like the latest 256GB emmc chips
.
ps: I just wish someone start selling like on ebay or some crap a full board+emmc just plug-n-play for a low price.