Just to clarify that point, it will not run on any card which doesn't support DX11. There are some pretty big changes to the rendering codebase being planned, which are both quite radical in terms of how rendering is done*, and which depend entirely on features in DX11. How all that will be put together has yet to be fully fleshed out, and is currently being prototyped, but will be entirely necessary for performance reasons. Can't give any specific figures, but I think you can imagine what would happen if you had 40 ships on screen in a battle with the current performance. So that part of the minspec is very much a hard minimum.
Keep in mind though, you basically can't even buy a desktop card below DX11 these days, without going to a brick & mortar or getting used parts. More than a year from now, when it actually nears release, the DX11 requirement could be met more easily than probably any of the others.
However, when it comes right down to it, yes, this will be a hardware intensive game. And interestingly, that's largely because of design reasons, rather than shiny graphics reasons. Where it will all fall in the end, it's too early to say, particularly since the prototype for the DX11 optimizations hasn't been completed yet.
*if it works as well as we hope/think it will, it will be something worthy of a SIGGRAPH paper or two