At this point you can't say anything yet about how classes will perform in MoP, since damage scaling still needs to be tuned, and we don't know yet what sort of damage each class will do in MoP raid/justice points gear. All you can do is look at the mechanics, and in my opinion ele shamans have some awesome tools in MoP to box pve:

great group healing & dmg mitigation tools
incredible burst CD with ascendance
incredible aoe cd with ascendance
instant LvB when lava surge procs

If you have 3x ele shaman, bosses are going to drop like how arcane mages do it currently when you pop ascendance with lust.