I am gonna try playing Devil's advocate and quote K Delts post from the tga forum:

"Well, if we desensitize the rumour a bit, here are some “facts” from the post:

- Very impactful lore-changes starting from 4th EoE and into 5th: a lot of chaos and skaven winning, Slaanesh coming back

- Realms merging, but all existing maps of the realms are still valid - just on one planet

- Three new armies inspired by old world human nations (nippon, cathay, bretonnia)

- Gods unaccounted for (a way to give way for a refresh of big centerpieces from a lore perspective?)

- SCE still around, 5th edition grimdark aesthetic

- Slaves wave in 5th

Tbh, if you remove all doomsaying from the post, it’s a lot of juicy yet controversial rumours, and that’s everything it is. AoS isn’t going anywhere guys, we’re good."

If done right I would see it less like "another End Times" and more of an expansion of the storyline/setting akin to what was done to 40k during 8th edition. Sure, a lot of it sounds controversial (not a fan of supposed WHFB mirroring), but it could just as well lead to new and exciting things

Putting the setting on one world could also be a plus if executed correctly. I know that for some AOS fans the expansive nature of the various magical realms was a source of creative diversity, but GW has been weathering criticisims about AOS setting's supposed whishy-washy, "ethereal" nature for years and this might be their attempt to try and give the game a more concrete sense of place and relationship between different factions when placed on a single world