Not really
I mean, just look at his homeland the old empire, sigmar’ heirs had all sorts of military weapons such as spears & shields, swords, halberds etc.
Nah thunderstrike are really just primaris Stormcast
By the lesson from 40k apparently GW is not gonna erase oldcast at once
TBH I guess they will buff oldcast in the 3ed as appeal to veteran players and then gradually support newcast supplement by supplement and 2 or 3 editions later there will be no one using oldcast
Then that’s the moment they will justify retiring oldcast, maybe not giving them rule adjustment as the first step.
IMHO, I personally believe and think GW has almost reached their practical limitation of factions they can have at once.
Which means beside the necessary new faction such as Mally and Grungni’s buddies (no read into these, we know they will eventually come despite how long it takes) we are unlikely to see splitting current factions.
The Siege of Excelsis really should be something like “all against destruction”, lore wise at least.
Under the influence of Goddrak and, potentially, Kragnos, I guess, ah, we will see every destruction force involved.
The later BR fictions have empathized that in Goddrak‘s great waaagh you can find every destruction faction, especially mega-Gargants as valuable personnels.