The easiest thing to do would be for EA/CG just to hand out rewards as if the guild completed the TB. Not max for anyone, more of an average of what your guild's star level is, or just match what you did last time.
Granted, that may take away for potential star gains due to guildmates boosting rosters since the last LSTB, but I still find this to be a better alternative than cancelling outright.
I find this to be the best deal for everyone involved. We get most, if not all, of the rewards we were going to get, it's most likely the easiest fix for the devs than them trying to force it into the already packed guild events schedule, and we minimize the potential for bugs with this huge update next week.
