Before the antitrust action Microsoft was knifing the baby and cutting off the air supply whenever anyone threatened their hegemony. Afterwards, a million little inroads were made that ended up making their monopoly irrelevant.

In fact the continued existence of Apple is a product of the antitrust action. Bill Gates struck the deal with Jobs in order to keep Apple alive as a "showcase competitor." If Gates didn't feel the need to keep up appearances he would have crushed Apple by ending the Office port.

I feel like the thing that really hurt Microsoft the most was the web, which made the OS far less relevant and has largely been their downfall. The failure of the mobile web seems to be largely why mobile OSs do matter.

Clearly, without the anti-trust ruling Microsoft was doing all it could to make the web proprietary, but the web wasn't pre-ordained to happen, and if it hadn't we might still be locked into Windows, regardless of what the anti-trust authorities did. Or maybe we'd be largely where we are today with the web having never happened and the focus shifting to mobile anyway.

And to look at Office, I feel like the real downfall of the network effects of Office was when PDF readers became ubiquitous and embedded in browsers, so that you could export a PDF from whatever editor you were using and send it to everyone and expect that they could read it.