Many current digital theaters COULD show 48fps with a software upgrade only (obviously with a cost to the theaters though...but you know they'll do it). So it's not as bad as when theaters were first cutting over to digital to begin with. But I would be surprised if more than 15% - 25% of the theaters do that early on.
Keep in mind that The Hobbit is leading the path, but Avatar 2 is coming right along behind it and will also be 48fps. Those two big tickets are going to inspire a lot of theaters to change over.
I just wish a 48fps NON-3D option would be available but I imagine most places that go with the higher frame rate are going to use it on the 3D version.
Not trying to start a 3D argument as I'll admit it's impressive. But I just do not find myself sucked into a film wearing the glasses. I sit and enjoy Avatar, for example, VERY much in 2D and can just fall into the imagery, story and 'fun' and not be part of this world for a few hours. But when I'm wearing the glasses I realize constantly that I'm watching a movie. A very cool movie, but still just a movie.
I'd much rather see The Hobbit in 48fps but if I have to 'go low' to get a non-3D version then so be it.