I told you. I warned several times Vecna's actions in Sigil caused the reset of the D&D Multiverse and now this is the excuse again to explain the current and cominsoon retcons in the revised 5e.
My theory is beside this we are going to see possible "crossovers" with no-fantasy franchises, for example Cybertronians dinobots vs terrorcons in one of the layers of Mechanus, or some cameo of Rom, the stellar knight, or a domain of delight within the Feywild based in the franchise Dreamoons. I wonder if we will be Gamma World, Star Frontiers and Star*Drive/Alternity within the D&D Multiverse, even when advanced tech breaks radically the power balance.
Other point is Vecna, somebody so wicked who wrote "Book of Vile Darkness" couldn't create a new D&D multiverse more "Grimmdark". I mean Vecna maybe caused the reboot, but he couldn't to controll it.
If alternate timelines and time-travels are canon in 5e, then we could see in DMGuild lots of titles style "What if..?" in Dragonlance and others. Dark Sun could be totally rebooted and reimagined, adapting to new sensitivities, and the new elements from later editions.
* I suspect the Weavers aren't a new creature, but an update or retcon of the "spellwavers".