Possible additional point: going into the 80s/90s (the last gasps of "alternative" personal computing architecture), there were not many widely-adopted standards across computing. This is why we all bitched about file incompatibility across systems etc. But now we have all of this great stuff: format standards, APIs, hell, even TCP/IP is a universal standard that allows all manner of exotic hardware to speak to the rest of the world.

I think something like Lisp/Smalltalk/SomethingNewOS machines might have another shot here soon, especially with the loss of gains from Moore's law