They are of course also in for future money. Reputation is an important factor for anyone who works on project-basis, which provides incentives to do more than the studio expects from you, at least if you are a young actor/producer/writer. Besides, I don't know the movie business but I am sure these folks have incentive contracts and their payment is based on how the movie performs.
Of course there exists the risk that the studio is in for a sell-out strategy, ie doing one movie which betrays Trek ideas, does a lot of money but destroys the future of the franchise.
It's a short-run long-run tradeoff and if the studio executives have poorly designed contracts based on stock options and stuff like that, this might happen.
But I doubt heavily so because a) Paramount saw what happens if you do too much Trek at one time and suck out the franchise, b) the franchise has the potential to make money for another 40 years and c) there are fans among the team at the helm of this production.