Assume OK and Ohio State will move to the 5-6 spots, but maybe not in that order. Georgia is now 4 and beats Alabama (probably not going to happen, BUT) Ohio State demolishes Northwestern and Oklahoma beats Texas on a neutral site. All that happening, if ND is the 4 team going into all that then:
Georgia #2
Clemson #1
Alabama #3
That leaves the possibility of either Oklahoma or OSU jumping to #4 after their conference wins.