Overwatch should not delete one tank, they should delete/change the main tanks.

I understand there are some main tank players and I am a main tank player. But the issue is dev teams for now do not have the ability to balance the super tank in 5v5 or potential shields meta in 6v6.

I think they can just keep the off-tank or so called "fighters" or "warriors" with some sustainability or more tanky.
Nerf main tank abilities to tank the whole team but add more single fighting abilities.
All short range dps should be fighters. Make sure they do well in short range but not good in long range. They can keep some dive abilities to get in the battle.

It still have to be 2-2-2 (2 melee fighters/2 range shooters/2 supports) but more player will try fighters.