If anything, I would not mind seeing someone else's take on classic space battles. IOW, not necessarily redo the battles and put them in the film, but if someone were to create improved effects shots, or even different angles on those battles.
There are really only a few of things I would change about the VFX in some of the Trek films.
1. The photon torpedo FX after WoK. IMVHO, ST:TMP had the BEST photon torpedo effects....period. They were mimicked somewhat in WoK, but then started going downhill from there. The effect was mimicked one more time in Generations when the Enterprise fired its one torpedo shot at the bird of prey. I would love to see all photon torpedo effects retroshot to that style in the other films. (I definitely did not like the torpedo FX in ST VI because they looked more like blaster bolts than any kind of torpedo shot.)
2. The phaser FX. AFAIC, WoK set the standard on phaser FX for the Star Trek films. I wish this was something that would've been emulated in the Next Generation series, and onward. Also, I wish shipboard phasers were more heavily used in VI.
2. Pretty much ALL of Star Trek V.