Put me down for the Cardassians too. One of the points in this thread is that I want the new films to do something different. Frankly I'm sick of the Klingons and we've had Romulans for the past two films. Doing Khan to me feels like a rethread and the feat of finding someone to play him will be daunting (they can go with the guy who played Robao).
The Borg can be presented in a fresh, threatening way, up the stakes a bit (maybe have Earth or a major character assimilated). But getting back to the Cardassians, they have a plethora of background and material to mine. One thing to do is to show how they became the militaristic society we saw in DS9.
You could be on to something here. Perhaps Mr Alaimo could play the lead Cardassian or maybe Casey Briggs as a distant relative of Damar?
I agree with the Tholians being in the next movie, I don't think that they can carry the film by themselves but a cameo would be appreciated.