I think the key facts about the GoR are this:
1) A team can change conferences under a GoR agreement, the GoR does not prohibit that, and the GoR obligations can still be performed by both parties after the realignment, so there is no default of a GoR upon conference change. Continuation of the GoR does not leave the departing school worse off, and if the destination conference is perceived to be sufficiently better that the two parties are willing to lose a little financially as they wait for the GoR to expire, they can operate for years under the former conference's GoR. All it means is that if an ACC school earning $20 mn/yr left the ACC for the B1G paying $35 mn/year to full members, they might get $20 mn/yr from the ACC (still) and $3 mn/yr from the B1G (or some nominal payment) until the GoR expires. The school is better off. The conference doesn't care, the $20 mn/yr is paid by ESPN. ESPN doesn't care much, it now has the departing schools B1G games which may be worth as much or more to it as their ACC games. The new conference gets the new team's in-conference road games and has full rights after the GoR expires.
2) The value of the media rights is diminished after a conference change, and ALL PARTIES (the conference and its TV network assignee that own the rights, and the school that departed, and the destination conference and its TV network assignee) can make more money if the GoR is terminated, with appropriate monetary transfers to compensate the losers. Collectively they have an incentive to renegotiate the contract. There is a high chance the GoR would be renegotiated.
3) The purpose of the GoR is a pass-through of rights to the school's media to a TV network. The GoR assigns media rights to the conference and the conference in a separate but aligned agreement sells them to a network (ACC to ESPN, for instance). The GoR is timed to terminate at the same time as the conference-network agreement because the purpose of the GoR is to give the network confidence it is not going to acquire rights to an "ACC" but lose rights to UNC/FSU/Clemson/Duke games when they move to a Fox-sponsored league. It assures that the network has rights to the same collection of schools throughout the duration of the contract.
4) Because this is its purpose, there is no reason for schools to have agreed to punitive clauses that cause them to forfeit revenue from their media rights when they change conferences. That would create a windfall for the former conference's TV network. The purpose of the agreement was not to create a windfall for someone in the event of realignment, but to prevent a catastrophic loss for the network in the event of realignment. I am not going to believe that schools agreed to such a thing until some informed official states that that is the case. None have.
5) I see no reason why the validity of a GoR agreement would be challenged in court. Maryland has an exit fee case against the ACC because the $50 mn exit fee was imposed without Maryland's consent, effective immediately, at the very time Maryland was negotiating its departure. That's totally different than in a GoR where it is clearly entered into voluntarily and with full knowledge of the consequences. The outcome would be negotiated.
6) Given that a departure from a GoR conference would not prevent a GoR from fulfilling its function, I don't understand the claim of Internet prognosticators that a GoR conference would never raid another GoR conference because they fear that would impair their own GoR. No, the GoR would not be impaired and the purpose of the GoR, extracting more money from their TV network partner, would still be fulfilled.