Mages and hunters are seriously cool too. Really, but in terms of 5 man and utility, shamans are still the best overall..

They have more utility to cope in PvP situations, and due to having decent healing capabilities while being a dps spec. (At least when you are 4x elemental shaman). Causes 4x shamans to still be the best all round quad box. And they too are seriously fun.

In terms of mages, I would go 3x mage and 1x priest. Or as far as hunters to, 3x hunters and 1x priest. If you do that you will have very strong PvE capabilities and apart from vehicle fights, should do fine in battlegrounds too. Arena is another story, but it's not even certain if elemental shamans will do as good in arena as before. We still have potential. But I'm not seeing us reach 2k rating 'as easily' (not easy at all, just very possible. :P) as before.

As for multiboxers reaching 1900+ in 5v5, I think only one 5-boxer managed this, forgot his name. And quite a few quad-boxing shamans. I was 1890 myself, but never topped in gear (had 1050 spellpower and 390 resiliance tho, so pretty close to the best avail :P ). If I had one more week before the 3.0 patch I probably would have gotten 1950+. Still a bit sour from not getting the most awesome looking set in the game in full. :<