Well it would seem like a rehash to us ... but not to anyone else, because seriously, has anyone over 25 actually seen Wrath of Khan?
It would be brand new to all the new fans/moviegoers ... so problem solved, not a rehash.
Plus if you want a compelling movie, use the best villain ... it would be perfect.
Of course it would have to be written well, I hope they can pull it off.
I'm not worried about casting or execution, the Abrams and co are great at that.