As for the release window, she has stated that the game will launch in 2018 and considering how she seems confident in it, and how Nintendo has raised their forecast for Switch sales, it is entirely possible that we might get a one two punch of Smash Bros. and Pokemon Switch.
Nintendo still hasn't said much at all about its new Pokemon game for the Switch, but a bunch of rumours doing the rounds have suggested it'll revolve around electric-powered-mouse-thing Pikachu and the feline-like Eevee. Then, by 2017, overall download numbers increased to over 750 million a year. Nintendo hasn't given any indication that they'll air a Pokemon Direct this week, but that hasn't stopped fans from getting even more excited about the prospect of a new pair of games.
Though it should be taken with a huge heap of salt considering the source, a message on 4chan from an alleged Pokemon insider suggested that Pokémon Let's GO! "It will be an RPG with at least two versions", something quite regular for the franchise on Nintendo 3DS.
She goes on to hint that we could see Pokemon Go accessories for the Nintendo Switch as well. Pokemon Go Pikachu and Pokemon Go Eevee domains are apparently registered. Last year, Nintendo launched the 'Project Eevee' Twitter account, which exclusively focuses on the floppy-eared Pokemon. Hopefully, all the rumors will be addressed and we will have something decisive to work with. That could easily just be a deflection tactic to enhance the surprise when the real project is revealed at E3, but we'll see soon enough.
According to Rogers, who returned to talk about the matter on ResetEra, "a Pokemon game is releasing on Switch later this year".