Whatever the third movie will be, the bar has been set pretty high by the first two.
Of course they can and will do what they want, but I don't see how they can follow up STID with more phasers, torpedoes, and destruction against the Klingons, Khan redux, or whomever given the openly anti-militarisitic tone of STID. Besides, it's not what Scotty signed up for.
Further, STID ended with Kirk reminding everyone of the purpose of the Enterprise's five year mission and what Starfleet stands for in general.
When we catch up with them again, they'll be somewhere in deep space on that mission, so maybe this will be the "we're explorers" movie. I'd like it if the conflict revolved around something new that's not necessarily flesh and blood, deliberately antagonistic, evil, or has it in for the Federation.
Whatever they're doing, I hope we finally get to see them fully developed and hitting on all cylinders. As well as those actors fill the roles, that would be exciting.