I'm ready for something original.
So far we've had a revamped Mars line, revamped Space Police, and now revamped UFO. If they continue with this trend we are likely to see a revamped M-Tron next. Why M-Tron and not another theme? Because Mark Stafford has stated that M-Tron is one of his favorite classic space themes. And in one of the Brickjournal magazine issues there is mention of a spacy dumptruck that they can't show us yet.
I know that M-Tron (and the "M") was all about magnates, but I suspect that the theme could make a reappearance as a space-construction/mining theme. Or at the very least a resource management/gathering one.
Otherwise, we might see a new Ice Planet theme, lot's of fans have been waiting for one and were quite disappointed when Lego missed the campy tie-in with the actual year.
Blacktron was given a nod with the recent Space Police pirates, Unitron and Spyrius were kind of small and I am unfamiliar with their stories. Robo-force (or whatever) was also small and might work as a new mech line, but please, no classic-styled robots.
Insectoids? I didn't really like that theme though I bought some to boost my collection straight out of my dark age. Although I could see the theme working with Lego's new anything-goes attitude regarding minifigs. Give us an insectoid alien nemesis with some cool ships and vehicles (not insect-based, with the exception of a multi-legged mech or two). I think we might go for that.
UCS scaled space ships outside of the Star Wars line. That would be really cool. Would anyone buy them though? UCS works because its Star Wars. The Cafe Corner series works because the buildings are quality designs. So...a UCS-scaled space ship would have to been done right. What if it were based off a Classic Space design? Imagine a giant Uranium Search vehicle, or Alien Moon Walker...or FX Star Patroller? Something bigger? Why not?
A mech built to scavenge for his existence
58 minutes ago