Maybe the best (short-term) solution is not conference expansion or super conferences, but using the NCAA to update their divisions and subdivisions of member football schools.

1) Create a new NCAA Division "0" for football only.
2) Allow both Div 0 and Div 1A (FBS) teams as members in the existing ACC (and in all P5 / G5 conferences).
3) Conduct CFP / NCAA national championship playoffs in both Division 0 and Division 1A (FBS).
4) Consider realigning ACC divisions (Coastal and Atlantic) by Div 0 and Div 1A.
5) Award two ACC football championships, in Div 0 and Div 1A.

Proposed Division / Subdivision membership criteria -
+ Division 0
. - Minimum 50,000 home game attendance.
. - Award at least 86 football scholarships (95 max).
. - Offer at least 220 scholarships across all sports.
(averages over a rolling 2-year period).

+ Division 1A-FBS
. - 15,000 home game attendance.
. - Award at least 77 football scholarships (85 max).
. - Offer at least 200 scholarships across all sports.
(averages over a rolling 2-year period).

+ No changes to NCAA Division 1AA-FCS, Division 1 (Olympic sports), Division 2 or Division 3.

Key points -
+ Allow P5 / G5 conferences to have football members from both Div 0 and Div 1A.
+ Offer national championship playoffs in both Div 0 and Div 1A.
+ Offer a conference championship in both Div 0 and Div 1A.
+ Div 0 schools must play at least 7 regular season games against Div 0 teams (to be eligible for a national Div 0 championship).
+ Allow all Div 0 games (interconference, intraconference and with independent teams) to count in Div 0 conference standings.
+ Allow one FBS intraconference game to count in Div 0 conference standings.

FYI, these are current NCAA Subdivision membership requirements (link below):

Division 1, FBS -
+ Home attendance of at least 15,000 (on average, over a rolling 2-year period)
+ Provide at least 77 football scholarships (90% of the maximum FBS number of 85)
+ Offer at least 200 full scholarships across all sports
. - Or spend at least $4 million on athletic scholarships per year
+ 60% of scheduled games must be against FBS opponents
+ At least five home games against FBS opponents
+ One game against larger FCS opponents may be counted toward the 60% requirement
+ Sponsor a minimum of 16 varsity intercollegiate teams (including football)
. - At least six men's or coeducational teams
. - At least eight all-female teams.

Division 1, FCS -
+ Provide at least 50% of maximum allowed scholarships in all sports
. - or at least 50 full scholarships across all sports (except Football, MBB and WBB)
+ 50% of scheduled games must be against FCS or FBS opponents
+ Sponsor a minimum of 14 varsity intercollegiate teams (including football)
. - At least seven men's or coeducational teams
. - At least seven all-female teams.