Imo the problem is different. Very often an mg, pak, mortar crews or infantry won't be full health.
That is 100% on you then, ost has multiple methods of forward healing and reinforcement stock.
Your scenario is highly unrealistic. Axis units will be fighting other frontline units while ISU will be adding damage. If ISU deals 80% damage, any other frontline squad will easily finish the job ar ISU will finish off a squad that is fighting other squads.
Its the exact same case with brummbar and brummbar is much more oppressive because
-it arrives earlier
-it costs much less
-it shoots twice as fast
-it always hits, contrary to ISU which has highest scatter values in game
We've just had a tournament where 1 of these units was used predominantly and performed above expectations consistently. That unit was not ISU. If ISU was half as potent as you try to claim it, it would be used more often.
Panther won't beat ISU unless Soviet player just lost all his support. Panther will be likely snared when diving and ISU will just shoot from afar adding additional damage, or will use mark target (imo then it deals even more damage than elephant).
Flank it.
Do not go in frontally against all of the support that will stand IN FRONT of ISU and don't suicide a single panther, where is your own infantry support to clear ATGs?
If Helping Hans can deal with ISU using only Pumas, you certainly can do the same using panthers.
Both above scenarios are very likely. The problem is that ISU will be able to do both jobs from 70 distance. It is a balance problem imo. It is too good at dealing with all threats.
While using stuka on vehicle is indeed unlikely scenario, ele itself hardcounters ISU badly, mark target or not, Ele will destroy ISU before losing 30% of own health consistently.
And no, ISU can NOT do both jobs from 70 range, its AT, as already established yet you chosing to ignore it all the time is OK at the very best and in context of all AT units in game, its plain bad, moreover, since you already forgot it, ISU needs to switch ammo, it means it can do AI OR AT, it can NEVER do both, because it doesn't work that way.