CBS will become interested when someone with credibility makes a viable pitch that includes a good argument for Star Trek being on Showtime, or Netflix, or sold to FX or whatever the plan is.
That's the biggest hurdle, where is it going to go and why should CBS believe it will make enough money to be worth bothering with? I'm sure there are many different ways a viable pitch could be constructed. Someone just needs to decide on a plan and pitch it.
Waiting to confirm that the second movie is a hit, is a good plan. That will make the case to CBS better than anything else I can envision. Everyone buy ten tickets apiece, even if the damn thing is about Khan!