I know TLDR.
I heard this week that if Tennessee was to win the National Championship this year, that would be 4 difference teams from the SEC that has won it over the past 4 years. That is incredible. So that led me down the path of what other conference could even do that. Currently I believe there is none, but you can usually see what conferences could accomplish this feat in the future by looking at the past. For the most part since 1970 there are only 5 conferences and some independents that have won a National Championship. The ACC, BIG10, BIG12, PAC10 & the SEC. Of those conferences, who has had 4 different members win a NC? I looked at what conference the team is currently in and not where they were when they won the NC. Since 1970 only 2 other conferences have had at least 4 members win a NC. The BIG10 (Ohio State, Michigan, Penn State and Nebraska) and the ACC (Florida State, Miami, Georgia Tech, Pitt & Clemson). I digress, If you took Nebraska out of the BIG10 discussion it would only be 3 from that conference. Nebraska has not won one since joining the BIG10. So in theory, the only other 2 conferences that could possibly pull off this feat are the BIG10 and the ACC. Now currently that seems like a distinct impossibility.
Other facts. The SEC has had 6 members since 1970 to win a NC (Tennessee, Georgia, Alabama, LSU, Florida & Auburn). In those 52 NC's the SEC has won or at least shared in 20 of those NC's. The PAC10 has had 3 members win a NC since 1970 (Southern Cal, Colorado & Washington). The BIG12 has had only 2 current members win a NC (Texas and Oklahoma).