bush is out, so it's kasich left standing. and, in the end, that might be what gets him the nomination.
but, trump currently has very large leads in basically all of the northern and swing/moderate states. it may work out to a time issue - kasich may have needed bush to drop sooner (or, more fairly, bush really needed kasich to drop sooner).
if we end up with trump/cruz/rubio left standing?
the reality is that trump is the most moderate, and the least scary of the three.
...and that's actually why he's winning, too.