Given how they finally got their heads around nerfing superheavy shiny toy units that invariably ruin late-game tactical fun, yes I do have hopes for balance.
People are just saying that balancing towards 4v4 would really screw up the balance in 1v1s and 2v2s.
Not if 3v3/4v4 balancing mechanics are made to be map-related. Let's have 3v3/4v4 maps feature less resources and lower pop cap -- that would have no effect on 1v1s and would improve large team games immensely due to there being drastically less number of instawipe/super long-range units on the field at the same time.
A system that is broken can not be fixed by introducing more features on top of it. Instead of more doctrines/units/abilities we need a system that would (1) Maintain the full efficiency of infantry and light vehicles on the field until the very end of the game, (2) Limit the number of medium (to a lesser degree) and heavy (to much bigger extent) armor in team games via their pop increase/fuel income decrease/other measures, and (3) Nerf the AP ability of heavy AT armor.
Less armor + less instawipe units would mean a win for tactical and measured games.
Agree with the OP regarding the impotence of medium tanks once heavies hit the field, especially in team games. I think the question of actually which medium tanks should have been made as prime units for factions is less critical.
Everything is relative. CoH2 does not have to have absolute realism in order for us to claim our perception of WW II combat will be ruined by experiments like the one mentioned in this thread.