I don’t think nerfing tanks is a good way to make Tanks fundamentally more popular.
As per usual, I’m kinda stuck on my most recent tank balance idea, where if you down the HP on barrier tanks, weaken fortify/grasp, and move Mei to the Tank role.
Then there’s nothing stopping a 600hp Roadhog/D.va speedboosting+Matrix into close range on a 350hp Sigma/Orisa, and the Hog/D.va would probably have the upperhand.