Ballmer may have hurt microsoft, but they are still alive and well. The truth of it is that for a lot of things they do, there just isn't a competitor, nor will one arise soon. No one is replacing excel. As for windows -- there are a couple of niches where mac or linux could step in, but for most of them, that just isn't an option. Azure, typescript, vscode, ms office, office 365 are massively successful.