This is some seriously delusional thinking. Microsoft not critical or relevant? What are you smoking?
First off, IBM is still here if you haven't noticed. They got out of PCs, but they still do lots of other stuff and are a huge and profitable company.
But back to MS: they absolutely are critical and relevant, because everyone's PC runs on their software. That isn't going to change, probably ever. If Windows 10 couldn't convince people to dump them, nothing will. They might not have gotten anywhere in mobile devices, but that doesn't matter because they still have their Windows and Office cash cows, and those aren't going anywhere, and there's no threats to them (do you see businesses switching all their workstations to OSX or Linux? Nope).
MS is doing the right thing: cut employees, and cut all long-term investment, and just keep slapping some new lipstick on the Windows and Office pigs. Corporations in particular will happily continue to pay through the nose for MS's enterprise products, and consumers are happy to use Windows 10 with its built-in spyware and advertising which MS makes money from indirectly. MS doesn't need to invest long-term, they just need to keep milking their cash cows. They can do this indefinitely, because the whole Windows 10 experience has proven, without a doubt, that customers simply will not leave that platform no matter what, and no matter how much it costs them.