Sure, but first and foremost okw needs a cheap recrewer, because kategame stums and obers needs nothing more to complement, and we aren't considering call in infantry.
Well a proper change should consider the whole picture, callins included.
And obers do actually require a bit of a compliment, much like sturms, in that they need acreening, cheaper units or they lose their cost effectiveness.
But volks do fill the role of a cheap recrewer.
The bolt action only version of live volks is a fix to all issues and is now possible with buffed mg34 and flak ht.
This is more or less the crux of it. Volks, with only their bolt action rifles, fit the role they need to for the OKW faction.
Their STG upgrade currently simply improves their all round effectiveness/mitigates their weaknesses. A full smg package would have situational utility, synergy with okw callins, and support the faction by filling a role that is actually largely unviable for okw.
But more than anything, full smgs instead wuld mean OKW players would/could leave volks unupgraded, which is where they are actually a balanced unit for the faction.
But like the above poster said, incendiary nades are a big factor. Normal nades for volks I think should be the case, with theincendiary being only doctrinal, or with the smg upgrade, or with vet.