I don't think TWI is onto a good thing with this "levelling up" system they introduced. People will always demand more levels, and from what I've seen the game is getting more and more unbalanced as people progress.
What will we have 6 months from now on? Lvl 8 people running around with one-shot railguns racing for ZED's around? It's already the "survival" part of the title is only true for ZED's.
The problem I see is there's no incentive to play this game other than levelling up, and TWI just can't catch up delivering enough levels while keeping this game balanced.