I do agree with everything you said except the call-in meta changes, I don't think limiting is a good option. I think players should be persuaded to use different tactics by making them viable. For example as Soviets, if you have good late game units you would not wait for call-ins, or as Ostheer if, as you suggested, you go T4 you would not need a tiger.
About other units I agree with your statement, although I have to say there are a lot more units which all need changes (Panzerwerfer, Brumbar, SU-76, all MGs, etc).
It so sad to see people saying "Relic will ignore everything the Players want and Keep the retarded meta. Threads like These are hopeless.". And you know what? They are right. Every single patch we wait for that big change but... well let's wait and see.
The call-in meta exists because heavy tanks are simply easier to use than stock units. You can keep on spamming them without any negative consequences, which is just dumb.
If T4 for Wehrmacht was easier to reach, as I suggested, people wouldn't have to rely on call-ins, so a limit on heavy tanks doesn't change anything here.
Soviet T3 and T4 units are already easily available. If they're not good enough to support call-ins like ISUs or IS-2s, buff them. I think they are good enough as support units but I don't care if they receive some buffs.
I actually think Wehrmacht is designed to have units that don't execute a supportive role for heavy call-ins and that Soviets are designed to rely on call-ins and use their stock units as support. That might be wrong though.
Anyway, there are more units that need some love, just like you said.
Fixing the issues I mentioned is a huge step towards improving the game IMO and I really hope we'll see a great patch in January.