That makes sense Slaanesh in Januray then I will go with Eldar and Aelves in march-may, I think Ynnari will get some kind of release - maybe 3-4 box release and then they will release one of them Aelves factions - Angelic Hysh Elves or Malerion Aelves. Also it's kind of interesting what Malerion is doing we know he created his Aelves, we know he has huge city in Uglu but that's it and I doubt we will learn much more anytime soon (for sure we will know more about Teclis soon).
Also what's interesting how GW with AoS made Slaanesh this arch-enemy of Aelves, back in WFB/End Times he was there but he wasn't preying on them, there was Cult of Pleasure, Elves were killing each other but he wasn't anything special. In AoS they made him somehow like She Who Thirst in Wh40k even know he is close connected to all things Elves. That's why we might get huge release maybe even with new starter sets for both AoS and Wh40k with Slaanesh vs Hysh Angelic Elves and Slaasnesh vs Ynnari. I think Hush Elves will be first just because HE was one of the most popular armies and they could be ultra good Order force and will look amazing for sure but I expect kidn of HE aesthetic turn up to 11. (which is possible as Avatat of Manthlann look like Lother Sea Guard Lord on steroids).
Also Eldar will need to get something as well and the timing would be perfect I think GW may push Ynnari more as In doubt they want to release all those aspect warriors for Craftworlds in plastic anytime soon, it's better to release double kits or even kits with possiblity of assembling 3 different units this way they can basically build up fresh Ynnari range with 3-4 kits along with using some CWE, Harlequin and DE kits.