Until Linux can just let users double click and install .exe files from Windows. The average user will never touch it. People will just stick with what they know, even if it's been neutered by being made into an online service.
That said, I don't see Microsoft doing that for some reason. There are just too many things that aren't suitable for an online instance of Windows. Not to mention that lots of areas don't have a good enough network connection to make something like that viable. They'll almost certainly continue to offer an installable version of Windows for a long time still.