Could you give a an argument as to why PIV is necessary?
It has the (weaker)characteristics (AI and AT)of a stug and ostwind combined.
Well if the PzIV cost me 200 fuel and 500+ Manpower you have an argument.
I already said why it's necessary. PzIV can't compete in T4. You might as well delete it from the game. The reason a PzIV is build is because it's a mid game unit. You entirely cut out T3 by removing it because a StuG gets shit on by infantry, an Ostwind gets shit on by tanks, a PzWerfer adds nothing because the game is still extremely dynamic and there are no static fronts at this point in the game.
If it is dominant now its more due to bad maps. When there are (comunity made) new maps that are smaller and have more shot blockers SU-85 will be a lot weaker.
So, you want to balance the game
now based on something that hasn't happened yet and may not even happen, and even if it did wouldn't happen for months?
No. No. And no.