Honestly dumb move.
By July 2022 it would have been 5 years since splatoon 2. This not like what level 5 did to the Yokai watch franchise. In fact Splatoon 2 released 2 years after splatoon 1.
Imo they released splatoon 3 beacuse it is easy to make since they reuse assets from previous games and can easily make a profit (Splatoon 2 did 12million). The player base must have been declining as each year goes by. They also probably have many ideas to implement in the next splatoon game, adding it as a free update on Splat 2 wont give them any money to pay for it.
Judging by the youtube views on the english and japanese trailer, this will be another successful Splatoon game. Treat it like how the 3DS got 2 new Fire emeblem games and 1 remake of a FE game.
And Splatoon 4 at launch year for Switch 2 is also still possible.
Pocky Lover Boy!