Due to WFA tech structure, Volks & upgrades have to hold out against each of the following potential threats (both individually and as a combination of said threats):
- Penals, with de-facto mid-long-range good performance
- Tommies, with de-facto long-range performance
- Tommies & Brens
- Riflemen
- Riflemen & Bars
- Riflemen & LMG
- Conscripts
- Conscripts & PPSh
So, IMO, the only two upgrades that would work for that would be either:
- An LMG42 upgrade; in that case we also give OKW access to T0 weapons and effectively remove them from the game, because now they've become Ostheer
- The weird STG weapon curve they have which gives them certain ranges to perform vs the forementioned units for each matchup
I can't think of any curve that will work vs each of the forementioned threats, and I can't think of any combination of upgrades that would help Volks to fight.
If you think that forcing Volks to pick mp40 alone will solve anything, feel free to give it a whirl in DBP trying the firestorm doctrine. You can maybe use up to 1 squad of Volks max tactically, but upgrading all of your squads with mp40, or letting the rest of the squads unupgraded is suicide.
Sure, we could tweak the curves a bit if necessary, e.g., cost, to prevent snowballing, and fire-on-the-move performance to prevent blob-ability. However, volks need to have a role in the late-game which is ideally complementary to Obersoldaten, without turning OKW into Ostheer v2.0.
What if Volks became a long range/close range squad with anemic damage at medium range?
Laser accurate but low damage Kar98Ks, and a single model with a buffed SMG to represent a squad leader. They trade very evenly in long range fights (except against UKF) and trade well in close range fights, but lose hard in medium range fights against Penals and Rifles because of hypothetically tweaked Kar98Ks with reduced damage. You could then choose between x4 MP44s which turn them into more of a CQC squad, or a single LMG34 upgrade. There is defintely overlap with Sturmpios if this ever happened, but then Sturmpios could have a more defined role as AT/support infantry.