Infinity engine is a very nice engine, I love how they approach building galaxies, nebulas, and star systems in general, very very clever. They could make the terrain more realistic but ultimately they are building a space sim so its not really designed around FPS on terrain surface but they definitely could do that.
The issue with Infinity is its development state is largely unknown half the time and from what I have seen I am completely surprised they have not got a beta SDK out by now. I'm wondering if they are sorting out a deal to sell out to a private company? (bye bye indie devs), but who knows. Will see what materializes by end of year, they really need an alpha or something out, however based on allot of the comments in the forums, things are kinda in limbo...
My dream would be to have Outerra + Infinity + Unlimited Detail all combined.. One day they will as truly the tech MUST go in that direction (any other direction is backwards).. Eventually we will have a galaxy engine that caters for everything and nothing else is required, the birth of the holodeck base construct!
...
Anyway we are a long way off from that, but it may happen, lets see if we can all just get along first