Safari isn't the new IE for one big reason: it's the only rendering engine on iOS, which means if you want to support mobile web, you have to support it, and that won't change anytime soon.
The US antitrust lawsuit was also about using their desktop OS marketshare, and the bundling of IE with said OS, to drive companies towards using IIS at the server end.
Damn it, Microsoft basically coined the expression "Embrace, Extended, Extinguish". Meaning that they embrace some standard, then extend it with MS specific behavior, then extinguish the original standard via creeping incompatibilities.