You can’t just throw in more RAM without having the rest of the GPU architected for it. So there’s an R&D cost involved for such a design, and there may even be trade-offs on performance for the mass-market lower-tier models. I’m doubtful that the LLM enthusiast/tinkerer market is large enough for that to be obviously profitable.
That would depend on how they designed the memory controllers. GDDR6 only supporting 1-2gb modules at present (I believe GDDR6W supports 4gb modules). If they were using 12 1gb modules, then increasing to 24gb shouldn't be a very large change.
Honestly, Apple seems to be on the right track here. DDR5 is slower than GDDR6, but you can scale the amount of RAM far higher simply by swapping out the density.
