GE I - III was introduced May 11, 2016, ToR was introduced July 21, 2016, GE championships were introduced Sept 6, 2016, GE IV was introduced Feb 2017 along with the GE specific rewards.
Everything in GE is now 2+ years old. I'm hoping that means it's all ripe for a refresh. In the wake of HC, now more than ever. I don't think it would take much. Some level 2 upgrades, a few shrink kits, re-balancing rewards on levels and in relics toward less inventory stuffers, and maybe a chance at some diamonds in a rare relic. Make the level 2 stuff rare, hard to attain, and worth leveling ToR more to make it worth the continued time and effort.
HC adds to the value of GE if you battle there, but there's not enough battles to sustain a higher level HC. As it stands, having yet to build either Traz or ToR for various reasons, once my Arc hits 80, Himeji seems the 'best' next GB to build. I had planned on building both Traz and ToR next, but not anymore. Seems I'll get much better output per tile with HC, then use the greater output to hyper level HS for happy and even more FPs.