I'd really like to see xenonauts carried into space. Maybe campaign style where you take planets from the aliens. Most of the mechanics could stay similar - radar in a solar system, bases built in a system. Intercepting aliens that are already there and stopping new ships from entering and re-supplying the system. Taking a planet can be a series of raids on bases or attacks on defenses. Perhaps allied aliens or indigenous aliens in a planet/system/multiple system. Hostile planets - need to research new armor, ground survival equipment and techniques, new weapons for dealing with hostile plants, animals, etc. Maybe space battles with multiple ships.
Personally I'm interested in the game for what it is now, graphics won't make me want to buy a new version.