This info is from the Warseer forum and the summary thread of Chaos Daemons rumors by Harry:
This just in from Rixitotal who has read next months White Dwarf:
"So in next months white dwarf there is going to be a leaflet with updates for Codex daemons and daemons in fantasy.
Some changes to old units, flamers are now only S4 in fantasy and some units have had point changes. ect.
Also new units slannesh massive chariot (2D6 +1 impact hits) and other weird chariot thing in 1 kit. the other thing looks and acts kind of like a mobile meat lawnmower. This is in both games and acts like a chariot in 40K.
Soul grinders are coming to fantasy! has T7 6 wounds and a load of upgrades for its shooting. looks pretty mental.
The model (40K kit) in the white dwarf and leaflet was on the same base as the giant goblin spider.
New models for plague bearers (really really nice, some have fly heads)
Screamers (look similar but with lots of eyes),
Nurgalings (looks like a pile of funny little germ monsters you might get in a dish washer advert).
More confirmation of this and some more details from my inbox:
Chariot kit has two builds. One has four daemonettes and a herald called an exalted with a big whip. The other build has the exalted on her own but the chariot is dragging spiked / bladed rollers behind it.
Soul grinders comes on the same base as the Arachnarok spider. Shooting attacks. One attack works like grape shot but can be upgraded. Another works like a stone thrower.
Blue Scribes gets a mini. More Dais than disc.
More confirmation posted by thebitzbarn:
Well it looks Like August new releases are all Daemons.
Plaguebearers (Plastic) 29.00 USD (10 Man box)
Screamers (Plastic) 29.75 USD (3 figures)
Flamers (Plastic) 20.00 USD (3 Figures)
Seekers Chariot of Slaanesh (Plastic) 29.75 USD (1 Model)
Nurglings (Plastic) 25.00 USD (3 figures)
The Blue Scribes (resin) 40.00 USD
Also a relaunch of Old Metal Deamons into Finecast and then on 18th of August a relaunch of Fantasy Beastmen in Finecast
Further Down The road:
All 4 greater Deamons will get plastic kits (with head/weapon options plus wfb/40k specific bits on sprues) and that there will be "resin conversion packs" to make "named greater Deamons". (Hastings) No idea of timescales on this. I am not expecting them to arrive together Or with this wave. (Harry)
Jes Goodwin is rumoured to be doing the Bloodthirster. (BRING IT ON! ) No timescale for this. (NatTreehouse)
Comment: Nice to see some new stuff for the Daemons and I really like these mini updates to an army similar to the one last year for VC (with wraiths, banshees and Terrorgheists). Plastic Plaguebearers at last, really like the old metal ones though and hopefully these will look cool as well. Also nice to see new and plastic versions of screamers and flamers, both of which may find a way into my WoC army as unitfillers/mounts etc. The biggest things though is the new Slaneesh Chariot which sounds really cool actually, also Soulgrinders in Wh fantasy?! From the text I don't know if it is going to be a new kit or not, but hopefully it will as I don't really see the current Soulgrinder fit into a fantasy setting, it's a little bit to much machinery and high tech. But anyhow, cool idea and hopefully it will look nice in a Daemons army.
And here's a list of all the new releases next month which I also found at Warseer: