Enlisted is doing just fine. WW2 shooters, especially F2P ones with a progression system like the one in WT are bound to fetch a smaller playerbase, but 6000 player peaks on Steam alone is a good amount. Of course it is less than what Battlefield games are fetching, but those are well established mainstream games.
There are good reasons to keep the game seperated, they didn’t just develop Enlisted seperately because they felt like doing so.
- It is way easier to balance the two games seperately
- Each game can get a seperate ESRB/PEGI/USK/FSK/whatever-rating (12+ for WT and 18+ for Enlisted)
- The level of complexity for different mechanics and gameplay elements can be much deeper when there are fewer aspects to factor in
- The servers can be more specialized to reduce loads for the different games’ needs
- The spec requirements for the two games can be kept lower as things that are needed in one game can be left out in the other
- Development overall can be much simpler, as there are fewer things that could potentially break when working on seemingly unrelated things
Neither of those things is going to happen, it makes more sense to keep both games running seperately. Enlisted is profitable enough to keep it running and War Thunder is better off without playable infantry.