Pretty much with Ckraine said, it's the choice of the Directors. But eh, we're players too, we can suggest anything we want, but just don't get out of hand by the word 'anything'. But it'll most likely be what the Directors have to say.
Edit:
You know, it would be better if you guys would just forgot about zombie survival. Well, if I think about it in this way, say, my favorite server TNT was shut down and never moved to premium, I would hate this idea very much, would literally just be very sad if this were to happens. There's always something to do rather then having arguments about this whole thing, it's really sad to see this. Not all classic servers will be implemented into premium, plus, it also won't have the same in-game mechanics since classic and premium are different. Lava and TNT were moved to premium, but they aren't completely the same as they were in classic. Plus, as I said above, it'll be the choice of the Directors in what server will be moved to Premium.