The elementalist would be like a wrestler. He would make a wall - and then make the wall attack you like a python.
I'd also like to see them be able to shape the battlefield itself. Like create high ground and ditches in the blink of an eye.
I'm hoping that for the Elemental power source, we see more use of zones.
This would make a very interesting defender. Imagine a defender that uses implements instead of weapons, and primarily does his job by throwing small zones centered on him that slow, daze, mark, immobilize, etc. Almost make him magnetic, in a very literal sense.
Sounds like a warden to me.A starting point may be a reskinned druid or shaman.