Microsoft x86s deep enterprise legacy is going to take time to be replaced. But product replacement cycles are pretty short. Microsoft could easily move a lot of their customers to ARM if they wanted to.
If I were Andy Grove, I would have bought a controlling interest in Microsoft years ago. But that is water under the bridge.
Plus,as you know, they have a serious strategic challenge to their business in the rise of firms like Apple and AWS developing their own Arm SoCs.
Also, one thing worth saying is that if ARM really takes a proper share of the market it will obviously make x86 less popular - this works in both ways because it also clears the way for Intel to try other things of their own (This is highly speculative obviously, but it's impossible).
The canary for Arm is if it's in the hands of developers (and not just M1).
Consider that Zen took about 5 years to do, when AMD were in a much weaker position than Intel are now. Intel's process problems are harder to deal with but they're not insurmountable as long as they get ahead for the next generation (Which they definitely have the cash to do).
Intel aren't anywhere near as doomed as commenters would have you believe on here or Reddit. Ultimately this is down to whether their leadership keep their heads up or are cynical.