Guiliani has pretty much peaked in his support. He will not benefit much as other candidates drop out -- that support will go mostly to his biggest rivals, which are probably going to be Romney and Thompson. If one of those two pulls well ahead of the other, he immediately becomes the favorite to win.
And, as for Thompson, he's managed to change quite a bit of this race without having gotten on that stage yet.
Rudy would pick up 80% of McCain’s support if McCain isn’t in the race. He’d get a share of Romney’s suppor (and vice versa). Fred has “changed” all he can change from afar. Rudy is, and will be, #1 until Fred gets in, and Romney will remain #1 in fundraising for some time-—he has that much of a lead.