That's hardly "leaving" or "shifting" just giving a chance to that demographic to use M$ tools, I code a lot in PowerShell and now we have PowerShell Core which also runs on Linux and iOS, good, now the geeks running Linux can also use PowerShell to administer Windows machines from Linux, how is that "shifting" or "abandoning" Windows? in my opinion, that's a genius move from M$, the other genius move was to open source PowerShell.
Regarding servers, hmmmm, most are Windows what battle is that?, also .NET Core is a cross platform open source, created by M$ (another genius move), things evolve and change and I welcome that, going back to my PowerShell example, now Windows PowerShell won't be updated but that doesn't mean is dead, it will live forever just like CMD.exe, but to be honest, PowerShell Core (or PowerShell 7 as of now) still has a long way to go to be truly a Windows PowerShell replacement.