The current leading edge processing products moved to chiplets because it was the optimal/only solution from a cost and performance perspecitve. If we assume that reticle sizes will stay roughly similar and process scaling will continue to slow, then it would seem that the future bends further toward chiplets...
Yes this is basically it. Reticle size is at the limit. Barring some sort of quantum optical revolution, we need chiplets to make more complex chips.
Also the amount of heat in a given area is rising. We need to spread it out or find some really innovative ways of dumping the heat.
I suspect as time goes on, prices per transistor will become absurdly cheap but you'll need to do things like have redundant hardware running half the time to get rid of the heat.
