The ISG abuse exists only because it's the only viable tactic these days otherwise your loss is almost certain, as OKW. Basically, after latest patch, I started with ISGs thing and then moved to other build, that involved T3 start (Puma building) and got seriously beaten. So I will return to ISGs 'cause there is nothing else an OKW player can do.
So yes, ISG needs fixing but then OKW must receive some buffs to deal with what allied are now.
I would nerf ISG but then I would:
1. increase AI capabilities of volksgrenadiers by just a bit OR make them less vulnerable. Alternatively I would make HMG34 a stock unit, slightly increase its damage output, raising its price by 20 MP and make kubel doctrinal;
2. slightly increase Puma ROF.
The idea is that OKW must not depend on a doctrine or on a specific build to be able to put a fight against recently buffed allied infantry.
Even the actual state of ISG suggests that in order to build an efficient and OP counter to Allied spam, for OKW is mandatory to start with medic hq.
Volks can already one shot any team weapon or emplacement in the game, can get shrecks that snipe infantry and counter vehicles, and the grenade is impossible to predict or dodge unless you are paying very close attention letting other units on the field sit idle or get wiped. I don't think they need any more buffs. I'd like to see relic make other OKW units viable again so we can cut back on the volk blobs supported by ISGs, it is getting really stale.