No, the losers on reddit want there to be but they're dumb.

you're a loser on reddit

Nothing atm point to them being on planet.

i want to kill them too, only fair

I don't think they'll ever bee in a tide game (by FS), and much less in Darktide due to them therefore having to make them work with the systems already in place (Armour tags, Scab already don't use Infested so should be alright), but the factions atm are made to be able to work with each others, which is why they don't all have the same units (though keeping that some faction replacement will still appear), and to be able to work on the same maps (Missions objective are pretty chaosy)

IF if do get a new faction, it'll probably new Cults, pairing new miniatures with a different Chaos God.

Tzeentchian Ash Waste Nomads: Outsiders of the Hives, that used to be the original inhabitant of the Hives, but were later were thrown into the Waste, now using the troubles to try to get back their ancestral homes (Miniature wise: Use the Ash Waste Nomads as base, but with Tzeentchian paint schemes)

Khornate Enforcer: Officer cult that originated from the Prisons on Atoma (which is where we were headed), where Enforcers have turned to Khorne and became bloodthirsty, using their past Convicts are fighting force they came out of their Cells to restore their orders to the Hives (Miniature wise: Use Palanite Enforcer and Corpse Grinder Gangs. As well as some Arbites for the Lord)

For Slaanesh don't really have any idea

thank you no