So, a simple F2P game available today, creating a bit of buzz. Later this year, a spinoff with a different kind of idea that works along Go and has some optional controller, basically targeting everyone and enticing Go players to get a Switch. Then next year a new core Pokemon that core fans will appreciate and Go players who bought a Switch for Let's Go could then be interested in, which would also allow for a long enough dev time to make something more ambitious and produce a significant jump by better utilising the new hardware.

I don't think they could've come up with a better plan, and it'll probably work out really well for them.