I like the idea of Slaanesh's struggle for freedom leading to him/her being torn apart while escaping. That way the status quo is shaken up, we get to keep the invaders/pretenders/seekers factions and it helps create more buzz for the Hysh and Ulgu aelves when all those juicy souls come spilling out...
Like a few others I'm guessing 2019's big Chaos release will be Undivided not Slaanesh. Too much Darkoath and Black Legion buzz for both gametypes (especially the rumours about a new Abaddon miniature).
As for rumours I see a new Lord Ordinator model is coming out. Considering we've already seen the new Knight of Shrouds model does this mean we could be in for a Fungoid Shaman on giant squig and mounted/alternate build warqueen when the Moonclan and Darkoath books inevitably drop?