Well, Microsoft is a near monopoly, and they're still developing systems, but I guess there is differences, due to the fact that if they didn't develop new software, then they would have no more revenue.
Chip development would most likely continue as it is, maybe a bit slower, but the benefits of competition is mainly price. But we can also say that it was because of AMD that forced Intel to give up their more gigahertz better buisness model and focus on efficency. Yes, competition is a good thing. But that still doesn't mean that if I was Intel and I had the chance to buy AMD, I wouldn't.
Eh, even if Intel wanted nVidia, I doubt they will actually buy them, especially with all the re-organization they've been doing (forgotten about the 10,000 layoff's already?) Yes, Intel would benefit greatly from nVidia, but is it worth the cost? Intel needs to focus on their core buisness model of selling processors and reclaiming market share before they can branch off more.
But who am I kidding, I'm an EE major, not a econ one.