Regarding the whole UT modes addition, there's a simple fix to counter (for example) CTF speed over durability priority.
They did this in Wow, they did it in god knows where else, but it's a functional system and works as it should.
- Flag carrier has reduced speed.
Game modes like "Domination" "Core control" etc are not in need of such balance, however fastest 'nauts would gain a penalty to capture rate, whereas slowest 'nauts would gain a speed bonus to this (not a massive one, mind you)
As for Assassination, or similar gameplay modes, the target obviously would have to get some sort of buff to prevent favorable characters to be the only option in said mode.
I would personally LOVE to see a survival mode implemented, but it doesn't entirely fit the MOBA concept regardless of overall modes. Just a coop game where everyone does not attempt to murder one another. That'd be great
Also, most of all i'd like to see new map mechanics added.
We already have a few, such as droid dispensers, anti gravity fields, a giant worm and whatnot, however there's so much options regarding this, it'd be a shame not to come up with new maps featuring new mechanics