**Warning ET spoilers**
First of all I do not think the End Times is going to end conclusively but rather be a series that is setting up the new Warhammer FB status quo as well as a tool to pull the Warhammer world into a smaller focus with the majority of events taking place around the Old World. They have already said they want Warhammer to be "complete" which means that really ET is the setup for this complete status. It also seems unlikely that they would be making models like Glotkin and Nagash for a one time only campaign. I suspect that the majority of new characters with models will survive the End Times (Glotkin, Gutrot Spume and the Maggoth Riders all survived) with only a few key players dieing (Archon for example).Do they? Which ones?
When you look at each race so far you have:
High Elves - Lost their homeland, moved to Athel Loren and united under Malekith (no more White Lions, the Phoenix guard merged with Blackguard, no sword masters of Hoeth, likely no more phoenixes, less dragons with no Caledor, no Lothern Seaguard etc)
Dark Elves - Lost their homeland, moved to Athel Loren and united under Malekith (no more Cold Ones, the Blackguard merged with Phoenix guard, witch elves seem unlikely under the new regime, shades have no blackspire mountains, war hydras and The Kharibdyss seem like a Naggaroth only thing etc). If Malus had survived then it would of seemed possible for him to be a new Witch King in Naggaroth but I'd say it's unlikely.
These 2 are almost indisputably merged imo
Wood Elves - Orion and Ariel are dead, they have accepted Malekith and Arielle as their new King and Queen and they have the High/Dark Elves living with them. The forest was devastated indicating a break with the "forest is alive" theme and Drycha seems to be acting as a malevolent force. It's possible they will survive as their own entity but imo it's far more likely they will be part of a new united Elf range . For example it's not hard to see how Waywatchers, Shadow Warriors and Shades would become a unified Elf Scout unit etc. Many Elf units across the 3 ranges are similar.
Ogre Kingdoms - They have lost the Mountains of Mourn and are emigrating and/or becoming mercenaries (Yhetees, Sabertusks, Thundertusks and Stonehorns all seem possible casualties of this). There has been mention of them leading Orcs in the Badlands and tbh they are a perfect fit for an Orc, Goblin and Ogre future book. It's hardly less of a stretch than reunited High and Dark Elves. Gnoblars are really just grey goblins after all and the Ogres have got to eat something while they migrate.
Orcs and Goblins - Orc and Goblins clearly have a part to play but as of yet it's unknown. Grimgor Ironhide and Skarsnik seem to be Gork and Mork's champions according to Wurrzag so I'd expect "empowered" versions of them. Given they have put aside their infighting they clearly have a purpose but what it is is not yet known. If the theory about a merge with Ogres is true then maybe Grimgor is going to go mano-mano (or orco-ogro) with Greasus Goldtooth.
Skaven - Rampaging all over the place. No reason to believe they will go away. Someone is going to have to deal with them.
Dwarfs - In a fair bit of bother but as always holding their own. I expect they will get in trouble, unleash a super weapon/god and then be back where they were at the start unless they do some crazy merge with the Empire after being chased out of the mountains.
Empire - The Empire is never going to change too much. They will probably end up in a slightly different form but I think they will survive mostly unchanged. Maybe a merge with Bretonnia but it's still not resolved enough with the big battles to come.
Bretonnia - The Bretonnians are on borrowed time imo. With half the population wiped out, Morganna le Fay dead and the Green Knight revealed to be Gilles le Breton who is now preparing an Errantry War against every disorder force in the world they are likely on a path to destruction. On top of all that Malekith just moved in next door! The only thing that gives them hope is Gilles Le Breton doing some sort of reboot on their King Arthur setting but it's likely they will disappear imo.
Lizardmen - The Lizardmen are mostly destroyed and the remnants are leaving Lustria. With no Lustria to support them their race seems almost entirely unsustainable (where else are they going to get Carnosaurs, Bastiladons, Terradon and Stegadons?). Unless the Slann have some sort of crazy trick up their sleeve (like clearing out the Skaven and settling in Estalia or the Black Marshes (an invasion of Skavenblight would be pretty fantastic)) I think it's likely this race is going extinct possibly after one last hurrah into the forces of Archon or the Skaven.
Beastmen, Warriors of Chaos and Daemons of Chaos - A whole ton of Beastmen have died and ET isn't even half over. They have been routed from Athel Lorn by the arrival of Malekith and tons more died at the walls of Altdorf when Gutrot rounded them all up as cannon fodder from the Drakwald. I strongly suspect they will be part of a future Forces of Chaos list. Warriors of Chaos and Daemons would be incredibly easy to wrap back into a combined force.
Vampire Counts and Tomb Kings - They are currently totally merged under Nagash who I don't see going away anytime soon. Either way a huge chunk of the Tomb Kings were destroyed and Vampire Counts are essentially the new undead. Setra is still around but I don't see the Tomb Kings ever recovering to be their own race again.
The end result of this could be a more manageable 8 faction game focused on the Old World:
Empire of Man
Dwarfs
Elves
Undead Legions
Forces of Disorder - Orc, Goblins and Ogres
Skaven
Forces of Chaos
It's all speculative of course because we simply dont know anything concrete but I think the High Elf and Dark Elf merge is the clearest indicator yet that this is a radical shakeup and not just a minor realignment.