http://www.cnn.com/2008/POLITICS/01/19/sc.gop/index.htmlI agree with this assessment. (Stu Rothenberg is a CNN Political Analyst) Damnit Fred! You made Huckabee lose
It depends a bit on what he says when he drops out. I get the sense Thompson is something of the southern wing of Romney, so him getting out w/o saying anything (especially while Paul, Huckasquirrel and Giuliani stay in) should help him... might be what's needed to prevent McCain actually. 
But it appears that if Thompson drops out, he might endorse McCain as the two are close personally.
Why do you think that? Thompson supporters are more conservative than Romney supporters (although since we're talking about Republicans, they all are). I think Romney is close to McCain in the ideology of his supporters in the South. A lot of veterans seem to have voted for McCain in South Carolina, irregardless of their beliefs on the issues. I don't know whether this will happen in other states down there.
Going from the moderate to the evangelical wing of the GOP race right now on a spectrum would look something like this:
McCain Romney Thompson Huckabee
I didn't include Paul because he could be in very different spots depending on the issue.
