Notice I said both "talk about it", and "build a nuclear reactor in space". You get huge wins from any mass you can find in space, and I would imagine a good chunk of a reactor could come from space.
First we really need to capture a good asteroid, though. And have the infrastructure to turn that into useful reactor building material.
My point is not that this will happen tomorrow. My point is that this seems to me to be fundamental to any real exploration or settlement of the solar system and that anyone who is planning on settling Mars or goodness help us, Saturn or Jupiter via chemical rockets is just crazy. Sort of like how we used to do math problems on when it was worth it for some computation to just wait for next year's exponentially-better processors and start it then, anyone running with that plan is going to be beaten by the initially-slower, but way stronger plans that involve building some infrastructure in space first, rather than trying to jump straight for the flashy awesome stuff.
... of course, that also means admitting there's basically no chance that any sort of space settlement can occur in our lifetimes almost no matter what the tech advances might be, because before we can settle there's a lot of building infrastructure that lets us build infrastructure that lets us build better infrastructure to do. And somehow figure out ways to keep this all paying for itself as it goes.
