OST will be an inferior UKF if something like that happens. The only thing that prevents OST from completely facerolling other factions is grenadier being inferior to other mainlines but in your suggestion you forgot Infantry sections in the equation.
But I understand that all mgs would get that in this scenario. I like the idea a lot. First, mgs become much less useful in later game stages because of tanks, inferect fire, smoke, etc. But they also become much less useful against frontally attacking blobbed infantry (because of upgrades, their vet, and yellow cover). I'd change it so that attacing an mg frontally should never be an opition (unless with smoke, etc.). The idea is really good as it would also make blobbing less powerful (this I'd say is what I'd like).