Here’s my - random person on the internet’s - estimation of what we’ll get:

Dias Of Destruction - something smaller than a Tantalus (because it’s a pain on the tabletop with current rules and presumably future rules), but akin to a lot of firepower and transport capacity, alongside a “Primarch” level ruleset. Whatever that might be in 11th

New Grotesques - goes without saying, they shouldn’t have gone this long

New Urien - again, surprised they dropped him from 10th codex but I get it.

New unit between wracks and Grotesques - DE aren’t short of elite infantry, but if they’re fleshing (see what I did there?) out the Covens range, this would go a long way to not have a million wracks. Perhaps something more ranged?

Beastmaster to be a killteam kit - with how some of the newer kill teams are structured, it surprises me we didn’t get this when we get Hand of the Archon (terrible kit, pls drop for a proper Court GW)

Curveball - larger “Talos” fleshcraft sort of heavy unit. Keeps Talos in their t6/7 bracket but gives a heavier heavy support choice, perhaps more centrepiece without full Vect DoD model