If Enlisted is truly dying as you are claiming, then what makes you think merging Enlisted into WT would bring in more players? People that play WT and are interested in Battlefield-like shooters most likely already play Enlisted and Enlisted players that are interested in WTs vehicular combat gameplay most likely already also play WT.
If you can’t see how the points I listed would be major reasons for Gaijin not to merge Enlisted and WT, then I think you are massively underestimating the effort required to combine these games compared to the rather small increase in income this merge would bring.
WTs dev team already is having a hard time keeping up with the huge amount of bugs, inaccuracies and balance problems the game already is facing. Having a fourth mode where not only aircraft have to be balanced according to the capabilities of tanks, but also both aircraft AND tanks have to be balanced according to the capabilities of infantry would be an absolute nightmare.
I’ve said this before, but not a single aspect of WT has been designed with infantry in mind. They can’t just copy Enlisteds code and paste it into WTs code either. Game development (software development in general) isn’t as easy as people seem to think, you constantly run into problems and the more features you have, the more things can and will break when working on other things.
But since most of this doesn’t matter and your main focus point seems to be WT running out of vehicles to add, let me tell you this:
Adding infantry doesn’t change the fact that the amount of vehicles that people are hyped for is limited.
Infantry isn’t going to keep the people that are only interested in the vehicle gameplay around, especially not if the infantry has the same progression as vehicles.
And as a sidenote, logistics vehicles could be added without playable infantry, but most of these vehicles won’t be moneymakers either way.