I was really scared of this when earth elementals stayed at level 70. I do think it is too early to say either way. There might be some gearing up to do before you jump successfully into heroics.

I am not much of a historian but when the first 5 shaman team showed up did anyone think they could do heroics?

edit: If it does work out that you need a tank. Well you only have to go 25 levels with a death knight. I haven't installed wotlk yet so I have no personal experience with it. I watch the videos of fuzzyboy and I see myself thinking I want to drop a shaman for a tank. But this isn't the way I want to play. I am dropping a shaman for a mage b/c the group of people I plan on doing 10 mans with decided it would be a good thing.

Why were shaman effective in heroics before?
1) Good Burst (still think we have this)
2) Surviability (we hit like a mage and wear a shield come on)
3) buffs