OKW would then be in a serious issue early game in early game engagements. The Volks would cost the same as Grens to produce and while they are cheaper to reinforce, they don't have the firepower nor the survivability with 4 men. And 20 munitions seems too cheap regardless for two more members even if total pop would be 8.
The automatics they get honestly aren't that powerful until the final levels of vet kick in to ensure Volks don't get stomped by Allied infantry late game. They are still considerably worse individually than Sturm StG 44s which are geared for short-range. Of course Volks still get two of them, but I'm not sure if it should be worth more than 70 munitions. Still, this needs testing to get the numbers right.
Some stats for comparison:
0/10/20/30/35
Volk StG 44: 7.97/7.1/4.38/1.85/1.03
Sturmpioner StG 44: 15.89/10.84/4.8/1.21/1.21
Rifleman BAR: 13.97/10.4/6.97/5.17/4.37
To be honest I love the change, it changes the dynamic of the OKW completely in a good way. Volks become quite valid as frontline units and without the 3-5 shreck squads that are instantly 4-5 which means sudden death for allied vehicles. Now they are solid AI(not overpowering) and can still deter armor with the cheap faust(15 muni), but its close range unlike the shreck that can snipe tanks at max range. Great change.