Nebraska CAUSED much of the instability you are referring to in their quest to be "better" than Texas. And by "better" I mean the most power and/or influence in the conference and the biggest share of the pie of payout. One of Nebraska's greatest "cites" as to why they left was because how favorable the Big 10's revenue sharing model was - which is a bull**** reason for leaving because we could have HAD a similar revenue sharing model. Unfortunately, the vote for that kind of change requires 9 votes or more, and there were always only 8 votes. Guess which school was always one of the dissenting votes? None other than Nebraska.
Nebraska was never in it for stability of the Big 12, much less in it for anything that would benefit the conference as a whole. They were in it to be the kings of the Big 12, and when they couldn't get that, they decided to stick it to UT, the kings of the Big 12. Further, they couldn't care less if they destroyed the conference and how many casualties they created along the way as a result - they were going to get theirs
All that being said, if Nebraska somehow decided to turn about face and return the Big 12, we'd be fools not to take them back. While the Nebraska brand is extremely tarnished from what it was in the 1990s and earlier, they are still a national brand. I don't know whether to say "fortunately" or not, but I would bet against that ever being a "problem" we would ever need to address.
The real irony, and what makes me laugh thinking about it, is since Nebraska was never going to be king of the Big 12, they left thinking they were going to be one of the kings of the Big 10. What they foolishly never anticipated is the Big 10 already has 4 kings - Michigan and Ohio State, and, to a lesser extent, Michigan State and Wisconsin. Nebraska right now is lucky to be at Minnesota's level in the pecking order - a level that is very much akin to Iowa State's level in the Big 12.
I can't help but love how much Nebraska's ego has destroyed them. Yes, they're getting paid. But what Nebraska really wants is power and prestige, and they're getting anything but that in the Big 10.