It depends on which direction the Republican Party and President Bush would want to go with.
Condi Rice would be pushed if they want someone who has been a very important member of the Bush Administration all along. The question is, would an inside member of the Bush Administration become a solid canditate for President? If yes, go Condi. If not, someone else like Sen. Brownback may be a wiser choice.
I don't know how likely it is, but I still say I'd love to see Rice run for president! Imagine a Republican canditate that is 1.) Black (you'd think the Democrats woulda beat them to THAT by several decades at least) and 2.) Female (creating an almost guaranteed Woman vs Woman presidential race.) Oh how I love irony!!