Hired muscle... nothing more, not much less.
Batista/Rey is pretty much done for now I think. Given how much WWE is dragging out how bad Michaels wants a rematch with the Undertaker at Mania, I doubt they will reintroduce an Undertaker/Batista feud in the meantime.
On the other hand, there has been a consorted effort to get Batista over as a heel lately. Of course, McMahon/Hart simply can't just be McMahon/Hart and they need to get others involved. Following losses to Rey and Undertaker being "busy", Batista isn't doing much right now. Hence he gets to be McMahons muscle. The whole thing is eerily reminiscient of the "Battle of the Billionaires" angle from a couple years back, without the money angle of course.
I'm not trying to take a pot shot here, but it was very visible that Hart had problems just cutting his promo in the ring last night. I'm sure multiple concussions and a stroke will do that to you. Added to which, both Batista and McMahon were very soft on Hart last night for obvious reasons. Nevertheless, I firmly believe Bret is in no condition nor position to be stepping in the ring again in any sort of physical capacity. Of course, last night proved that neither Hart nor the WWE agree with me.
This whole thing is building towards Hart actually getting in the ring again at Wrestlemania. At this point in time, Hart is very, very limited in what he can do by himself. Now that McMahon has Batista, it won't be weird when Hart "recruits" someone to even the odds. Whether that "someone" will be the Hart Dynasty or not is anyones guess.