Still, I don't see them being a monopoly as VIA still designs x86 processors to this day, and there are many operating systems that will run on ARM. Also, if I am not mistaken, any company can go out and make an x86 processor now, just no one has a desire to. In the eyes of a court, the fact that VIA still produces and designs x86 CPUs means that there is more than one player in town, and they don't care if AMD dies.
With that said, anyone can buy AMD up, it doesn't mean that the courts can force them to produce either an x86 or x86-64 CPU, sure a court could break Intel up, or tell Intel no more x86-64, but, I have SERIOUS doubts that the courts would do that.
If you say VIA doesn't really count, then IMO, AMD doesn't count either considering how far behind they have fallen in terms of processing capabilities.
It's almost like me sitting here saying, "Hey, I want to replace this part on my car, but it's a dealer only item and no one else makes it, that's a monopoly!" Not really true, the issue is, no one sees a profit or purpose in making that part yet, aside from the actual manufacture that made the part to begin with. That happens far more often with cars that are almost brand new off the line than you think. I still run into cars to this day where the only place you can get the proper brake pads are from the dealer because the cars are so damned new.
So no, Intel wont be considered a monopoly in the end just because AMD fails, and if the courts eventually DID consider it, one of two things will happen. We wont see ANY x86-64 CPU come from Intel anymore, OR Intel will be broken up, and we still wont see an x86-64 CPU. Good bit different than when the government forced Bell to break up compared to consumable items.