Championship games ranked in order of viability and sustainability:
1. SEC Championship. "The Granddaddy of them all" I say with a smirk towards the Rose Bowl. We were the first in D1A/FBS, it has always been a sellout and great tv draw, and the SEC is the conference with the most rabid fans.
2. BIG TEN Championship. Because their fans care about as much as SEC fans, and it's always been a well attended game with good ratings. No, it's not the same level as the SEC game, but it provides the Big Ten with a lot of $$$ and thus will not go away quietly.
3. Big 12 Championship. It was more viable in its first iteration. But when they saw they could live without it, it lost its luster, and now it's a guaranteed rematch since they already play a round robin schedule. But their fans are passionate, and as long as it's OU or Texas, it will be well attended and bring in ratings. And.... it's most likely always going to feature OU and/or Texas.
4. ACC Championship. It has never been well attended. The ACC truly is a basketball first conference and it shows. Clemson dominates the thing now and I don't see that changing soon. If Notre Dame ever decides to become a full fledged member, that could change things. They definitely would need to be placed in the division opposite Clemson. But this is a game that could be cancelled and I doubt anyone would notice. I'm sure it still pulls in some dollars for the ACC but it can't be anywhere near the top 3.
5. Pac 12 Championship. This game has been a disaster from the start. The Pac 12 utterly failed in the last round of expansion and that's saying something seeing as how the Big 12 nearly disintegrated. But those two things are related: the Pac 12 failed to get Texas to join, and that was what everything hinged on for them. Colorado and especially Utah fails to move any needle whatsoever. In today's rules, they would not have needed to add more teams to get a championship game and I'll bet they wish they would have waited. Now they've got 2 more mouths to feed and it turns out their fanbases really don't care that much. They have to play the game on a Friday night just to get any sort of ratings. It's never been attended very well. No one would care if they cancelled this game, but I suspect they'll keep playing it for the time being. It's moving to the new stadium in Las Vegas, but how is that going to make a difference when they can't get 30,000 fans to attend?