I will weep on the day when the great Europe is defeated by people being unable to use a slightly different spreadsheet program, word processor, or a file sharing solution.
But yeah, the argument about "adapt or die" is also way off base. Ideally it'd be a gradual migration, all low hanging fruit first, seeing what works and what doesn't.
You make it sound like the current Microsoft stack is so insanely great it will be impossible to replace.
Yes, change is hard, but there are also massive upsides in switching to something better.