If it had been you...
Imagine if you were in JJ's position, what would you do with the Star Trek franchise? Would you do the same?
My 1st idea. If it was me who was given this $150,000,000 Trek film to make, I would have proberly tried to avoid a prequel. I would have explored the 25th Century and bring in new characters and a new ship. Gene Roddenberry always moved foward and I wouldn't change the tradition.
2nd idea. With a budget like that, battle sequences could be huge and spectacular. A movie that would focus on the Dominion War in depth, really show the battles in full and from the perspective of others than the DS9 crew.
Here is to the undiscovered country