What happened to the Magic and other ideas

I'm thinking that the loss of magic could be somepony using Cozy Glow/Tirek's plan to rob Equestria of magic working. Add to that the Main 6 being imprisoned to keep them out of the way. My head cannon has all of the main six immortal because they became the bearers of the elements. This Diddn't end when Sombra killed the Tree of harmoy and glittering representations. The gems that everypony thought were the elements were more like the various lantern Corps rings. And when the gems were destroyed, until Discord reminded them that their power came from within, the mane 6 were alot like MCU Thor after Hella destroyed his hammer. And like him when they were reminded of where their power came from within. Which by the way they promply forgot about when the deadly trio (The Legeon of Doom is DC property alone as fat as I'm concerned) was threatening Equestria. Also they did MLP a diservice by not having Katrina making a reappearance before the show's end or are they habing her be the cause of the loss of magic.