If Planetary Annihilation amasses $1.3 million, Uber will add gas giants and new orbital units to the mix. Said units will likely include "a more expanded set of orbital recon units, space platforms" and others based on community feedback.
In addition to the stretch goals, Uber has announced several "add-ons" for the existing reward tiers, including extra copies of the finished game, extra beta keys and extra T-shirts. Three more stretch goals are in the works, though they remain "locked" at the moment. We're holding out hope that one of them is reserved for Jell-O planets.