And in that sense, there are really high costs to variety. Imagine a world where you need to be fluent not just in whichever two of RCS/CVS/subversion/git are currently en vogue, but also mercurial, SCCS, bitkeeper, Perforce, ClearCase, etc... That's a mess.
So sure, git might not be "your thing", but I strongly suspect you'd still prefer a git-only world to one where every project you want to tinker with uses a different SCM.
And of course I can only agree with your last sentence, a bit of standardization is a good thing.
So do I. I just think that it will be nice should there come a day where knowing git will allow you to deal with the majority of the positions out there. I do not believe git is a 100% fit for all organizations. I do, however, believe git is flexible enough to be a fit for, say, 80-90% of them.
I think git will become a de facto standard. Like all such things, though, there will be alternatives available and in active use.
At work I chose (yeah, there was no VCS in use before that) mercurial mainly because we're a small .NET shop, and a nice GUI like TortoiseHg is a big selling point when you're trying to encourage people to use such a tool. There are actually lots of developers who just <i>hate</i> using a CLI. And I don't know how things have evolved, but git was not known to be very windows-friendly two years ago, even apart from the GUI thing.