In the past, the only way I have seen COD successfully balance MGs, is like in COD4. Where they are stationary on the map, and have unlimited ammo and no overheating. It provides a good balance of vulnerability (you're stationary and everyone knows where the MG spawns on the map) but also you can lay down a ton of fire and suppress/control the map, like MGs do in actual combat.
W@W tried giving MGs deployable bipods, which was a good idea, but the pathetically small amount of ammo on the belt, combined with lack of damage, meant they were worthless as weapons compared to rifles and SMGs. MG doesn't really jive well as a carry-able weapon type compared to the rifles/snipers/smgs/shotguns. I think they work better as stationary map elements that the team can use to control the map.
We only have seen a small amount of weapons.
If the mg42 will be one. We've to wait and see. In WaW is was. Maybe this time only as a fixed gun and we get next to the mg15 the mg38 and probably allied lmg(s)
We also didn't see M1 carbine or the M1A1 variant, no gewhere 43.
That and the 30 cal. They used those is W@W as equipable weapons. Saw a video on IGN about the mtrying out guns at the ingame range. Teh yonly had very few to show. No Mp44, mg 42, no gewer, no grease gun, no KAR etc.
Hopefeully we'll see more soon.