I was surprised he suspended his campaign...I figured he would hold on at least through Texas and Ohio. I would not assume he would be the leader for 2012 though. If the ticket ends up being McCain-Huckabee, Huck could be the leader...or there may be someone else on the horizon.
It all depends on two things--the outcome of 2008 and what Romney actually wants. If the GOP wins in 2008 then who knows what will prevail for 2012-- McCain, the VP, or what. But if Romney wants to be president, he has a clear charge for the next four years--work to build the party, support active candidates, support conservative causes with actions not just words, and we will see four years from now.
If he goes away and heads up a lucrative CEO job and sinks from public view, then he's done. He can't get anywhere politically thataway.