Re: "Linux is pretty much the only viable alternative OS"
Linux certainly is, at the OS level. I am certain that, in time, Linux will be the Enterprise OS of choice.
But at the application software level, Linux is woefully undersupplied. LibreOffice works fine for me, but Calc doesn't have the polish of Excel's formatted tables, or the fun but useful things like Sparklines, not to mention that its charts are somewhat disappointing and lack every formatting option Excel charts have.
Writer is not much more evolved, has no themes, no header formatting, is basically Word circa 1998, albeit a bit more efficient and faster.
For the rest, a company migrating from a Windows environment will have a devil of a time getting apps in Linux that can compare with the ones they use in Windows.
So no, Linux is not actually an alternative and won't be until those gaps are filled.