I think anyone who ends up being 1st, 2nd, or 3rd (maybe 4th) will still be in the race for the long haul. Maybe 2 or 3 drop out after Iowa and another couple after NH and South Carolina. Though South Carolina is an open primary. It will be another month before we know who will be the remaining candidates. I think Iowa only matters for the lowest rung candidates. Just my opinion.
Kasich may 2nd in NH and try to hang on until Ohio. I can see 4. If we really have 3 in the 20’s here then the bar is pretty low to keep accumulating delegates.