What exactly is the point of these? They require over 1000 points worth of battalion tax alone. That's without any actual units. The minimum cost for units is going to be over 3000. Even for a super battalion that's rather excessive, and that's only the bare minimum.
I personally think GWs is alluding to some thing coming later down the road similar to apocalypse for 40k. ...or what @Erta Wanderer said lol
I don't think I've seen any in the other books though that were 4000+ points minimum. Most of the ones I can remember worked at around 3000-3500 points and then they were better than just minimum size (E.g. a horde unit would actually be at horde size, unlike the 6 saurus warriors and 4 skink units I've put in there that are all MSU). This one just seems like an even bigger waste than usual. Especially as the effects are halfway interesting for a regular battalion.
I really wish it was just the units in the battalion, and not all those extra battalions.... The effects are meh for Coalesced, okay for Starborne.... but they do make a 1 drop including a Slann/Starseer/Trog.
The worst prat is dual sunclaw requirement. This is the only battalion that needs more than minimal units size to be decent.