While that's true, I also think these things tend to happen as a gradual build up to the tipping-point effect where the zeitgeist shifts so suddenly that a massive player is suddenly irrelevant.

Microsoft is structurally incapable of making Windows better. Intel is intrinsically incapable of making x86 better (enough to matter). x86 hardware manufacturers are in a price race to the bottom, and there's no way around that.

Apple doesn't have any of those problems. Instead, more and more young people can afford and aspire to get a Mac. They want to buy software that works on the mac, and they'll want to write software for the Mac. The network effect compounds.