Like ElliotH mentioned, having a monopoly is not illegal. What is illegal is using your market power to drive out competitors and crush upstarts. If Intel is guilty of this[1], then they will face anti-trust hearings. If they're not, having a monopoly on x86 processors will not be enough for them to be punished.

On this one, it seems to be AMD causing their own downfall by poor management decisions leading to bad engineering practices. There's a lot of talent over there that is going to waste.

[1] I believe AMD successfully sued them for this in the past, but that seems to be over and settled.

What would you say they're doing that would justify such a suit?

Microsoft has a desktop monopoly with their 90% desktop market share. They aren't currently being sued. It was Microsoft's illegal tactics in the 1990's that got them in trouble. These days I don't believe they are doing anything illegal.