Skipping Tier 11, introducing a T12 which would consist of more modern tanks that would not fight against any other Tier but themselves.
IMO this is a good way to keep all the history yet bring fresh modern content to the game.
Using the same maps etc, making WOT into a 2 in 1 game IMO would be better than creating a whole new modern tank game to compete with other options.
T12 starting out with limited options would not hurt it IMO.
For example if only 1 Tier 12 tank is available and everyone is going around fighting each other in a M1a2 Abrams. fun
Modern tanks don't varry much so we can't expect Light-Medium-Heavy etc, so 1 main Tank class with potential SPGs should be enough.
IMO this makes things easy for WG to implement and users to test/ play and refine with feedback over time.
Players get modern tanks and WG get more money that they soo eagerly need*, With that said more publicity for WG and youtube videos of modern content to bring in younger players.
In the end more people coming in to play modern tanks and having historic content to go through as well if the Tank bug bites them.
P.S: Ofc these tanks will be implemented without all the fancy electronic nonsense, just tanks with a popable smoke screen if anything.