>>44448529If we're being honest BW2 itself could've been DLC for BW. If it were made today it certainly would/should be.
As for the sales, I cannot say for sure. SwSh being so successful means Game Freak will be less inclined than ever to change anything up less they want to. When you factor in Pokemon Go & Masters, GF is experiencing some of its most profitable years, only comparable to the original Poke'mania.
If it works, then it works, and obviously a lot of people are happy as sales would've reflected otherwise. On the other hand, being so profitable can also mean being able to take a risk and not suffer for it like a lesser studio would, so all hope is not lost.