I think Ill, and possibly Mich and Minn could be in play for the GOP — especially if Fred Thompson is the nominee.
Illinois no way. The states most likely to swing red, in more or less particular order: Wisconsin, New Hampshire, Pennsylvania, Michigan, Minnesota.
I doubt Illinois will. Since 1992 the Dems have been carrying the state by more than 10%. Hillary born in Illinois and Obama would more than counter Thompson and the Daley machine in Chicago will dial up whatever votes they need.