I don't believe the 6 conference champs rule will survive the next round of tweaks by the CFP committee. Look for them to lower it to 5, by name: SEC, B10, B12, ACC, and highest ranking among all others.
You can bet that the committee will--quite intentionally and deliberately--rank the champs of the Power Four (P4) conferences among the top 12 teams. The 'other' conference champ may often be outside the Top 12.
That means 11 P4 teams will get into the playoffs. Besides the 4 conference champs, there will be 7 at-larges.
As the years pass, there will be pressure to include any "regular season P4 champion who is not also their conference championship game winner." Sort of the way "winning the conference" can be accomplished two different ways in basketball.
I think most years, 3 to 5 SEC teams will make the playoffs. Very rarely, only 2 will. Even more rarely, 6 could. But usually 3 to 5.
What will it be this season? Impossible to guess. So I'll say 4: Tennessee, Georgia, LSU, and A&M. Yeah, I said it. Jimbo will have a resurgence now that his arch-nemesis pen pal Nick has left the chat. Heh.
Go Vols!