The reason why we're getting 2 entries so close to one another and still no gen 9 in the horizon is because they want to extend SwSh life cycle, consider this
>DoA online for BDSP, no multiplayer for PLA
they want to keep people on SwSh online and ranked
>no extended pokedex for BDSP
they want people to buy SwSh to access newer pokemon
>no DLC plans for BDSP nor PLA
they want people to buy the SwSh DLC, also
>HOME support for BDSP and PLA is coming AFTER PLA releases
Masuda and TPC purposefully hindered these games to boost SwSh sales even more and we're getting a final piece of content for SwSh, while there is no indication of a part 3 DLC up to this day, a final update containing the missing gen 1-4 mons is coming, and you will need BDSP and PLA to get them.
REMEMBER /VP/ WE'RE NOT DONE WITH SWSH YET, THE NATIONAL DEX WILL BE RESTORED AND SWSH WILL FINALLY BE COMPLETED BEFORE GEN 9.