I can tell you what there will be too much of. Melee dps.
There won't be enough healers, cause they get blamed for everything and too many people get sick of it.
There won't be nearly enough people willing to play support full time.
Generally you need
There will be plenty of ranged dps, too many melee dps
not enough healers and support
When you get raids started, you start with tanks, healers and support, once you have those worry about dps.
All your going to do is waste all the dps time if you just start grabbing whoever right away.
Personally I'll only heal for RL friends, in a random group I'll only play ranged dps as a chain class.