Rebooting Atlantis would be a good idea, but unlikely. Why not go to the source: The Ancients!
I think they might try a reboot of Atlantis - perhaps in some modified form (a couple of new players?).
Either that or a long hiatus. Bringing in a completely new "Stargate show" soon is too risky at this point for the investors.
This whole Stargate thing revolves around a singular piece of technology: The STARGATE. That device is and always has been the center of this story and the franchise, and with the exception of SGU, the premise has always been unraveling the mystery of its purpose, where it goes, how it works, who uses them and how/why they were built. So, why not take the story right to the source? That means finding Ancients or their last homeworld. Why not send an SG team through the gate and have them find a whole PLANET full of Ancients (preferably unascended)? They could even be stranded there. On that planet, we could see entire cities, factories where the stargates and Ancient ships were made. We could have ascended Ancients in the show, and unascended ones. We could re-introduce a new Atlantis from that point, or launch a whole new set of things from such a planet.
Whatever the new show was, it would have to be action/adventure with good drama. They could even make it dark and gritty, but forget about the character driven (soap) aspect. And NO BORROWING FROM OTHER SHOWS. Frankly, I kinda didnt like it when the earth people started building starships like the Daedalus and the Hammond which were loaded with beam weapons and transporters and shields (which were ALL borrowed from Trek). They should ONLY have the stargate, and then all technology added would have to be discovered on other planets. This means starting from where the movie left off, not where SG-1 or Atlantis left off.