Pretty interesting post, thanks for sharing ! I didn't see it being discussed very much but a possible fix for the damage issue would be to remove damage done by minions, basically you'd only deal damage with your tavern level. Obviously you'd have to lower starting health, but I feel like it could make the game more interesting.

Damage would be more consistent and you'd be able to control how your game goes way more, but you'd see close to no highroll lethal and it could be a bit boring for players who enjoy RNG fiestas.

It's also simple and quite intuitive, even a new player wouldn't have much trouble understanding it.

Another idea would be to slightly buff midgame comp in order to make power leveling worse, but it's a tricky middle ground since over buffing midgame would basically destroy other strategies and you'd end up with another just as bad meta. And I somehow fear that Blizzard's balancing ability wouldn't be enough to realistically achieve that goal

Then you could also change some core mechanics like having multiple hero powers or being able to heal, but overall it probably wouldn't feel great so I'm not a huge fan