If you want to set up new Traveller universes/game settings three main possiblities come to mind.
A) A more realistic space setting set up in the area near Sol two to five centuries from now. A fairly Hard Sci Fi approch which focuses on human exploration and settlement.
B) A hardish Sci Fi setting placed about ten to twenty centuries forward from now. Think Transhuman Space meets Traveller and gets wild.
C) A setting restricted to the surface of one planet. Picture a starship misjumps, the ship is beyond repair, no one knows where or when they are, and they must colonise the world they crash on to live. Luckily the starship was loaded with supplies for a colonisation attempt. However, the colonists weren't on this ship (they were waiting for their supplies).
This would be a low tech space story. The people would be trying to rebuild the technology they'd lost. Psions would be trying to get accepted as part of society. Some would welcome them, others fear them, others see them as tools to be used.
Descendents of genetically altered humans could make great "Aliens" for this setting.