Historic Football Powers not in the SEC/B1G that would bring value to both: Florida State, Clemson, Miami, Notre Dame
Other programs that could carry their weight in revenue in either the SEC/B1G and would bring value to both: North Carolina
Other programs that may get a look from either the SEC or B1G based on new markets: Virginia (B1G/SEC), Virginia Tech (SEC), North Carolina State (SEC), Georgia Tech (B1G)
May be included as a tag along: Duke (SEC/B1G)
I think this is the short list of anyone who still has a shot at joining either the B1G or SEC. Some have much better odds than others, but I don't think anyone else has a snowballs chance.