Stargate

SGU is so perfectly poised for a continuation at any point. Everyone but Eli is in cryo and we don't know what happened.

Some actors won't come back? Ok, the characters died in cryo. Some actors are sceptical about returning? Their cryo pods are stuck and can't be shut down. David Blue specifically won't come back? Eli didn't manage to fix the last cryo pod. Or maybe he's just missing, along with a shuttle.

Anything could have happened on the ship in the intervening time. Any plot device that's too powerful (like the stones) could go missing. Don't like the enemies that were being set up? That's cool, it's a new galaxy.

And of course, since it's not actually certain how long Destiny will take to cross the gap (maybe Eli had to slow it down?), this continuation is evergreen.