I would assume anything that got models in the End Times to be staying around for 9th.
This is what I think;
Considering that the leaks have been right so far, lets assume they are all right. That means one race will be a "powered armoured army of light". Likely that means the remnants of the Empire, possibly with the Dwarfs joining them to create a coalition, along with the other survivors of the human factions.
The merging of the Elves makes me think that the High Elves, Dark Elves and Wood Elves are dead, but something new will emerge from that. An Elven race that bears the hallmarks of all three Elven societies, merging the older values of each culture and adding new ones as they find their way to forming a tight-knit society.
The Skaven will survive. I refuse to acknowledge any kind of alternative.
Chaos will still be around, it wouldn't be Warhammer without it. The Daemons will remain unchanged, but the Warriors and Beastmen may find themselves quite changed, or perhaps even changed entirely as Chaos finds new followers to work the will of the Dark Gods in whatever comes next for Warhammer Fantasy.
The Undead may find themselves continuing in some form or another. The Vampire Counts, Tomb Kings and General Undead (Nagash) could form some kind of new necromantic faction that will try to continue the Great Work that Nagash began.