Is it though?
2018 1st party 3DS titles
March-Detective Pikachu (localization of a 2016 game)
June-Sushi Striker (also coming to Switch same day)
July-Captain Toad (also coming to Switch same day)
August-WarioWare (compilation of existing minigames)
2018-Luigi's Mansion (port of 2001 Gamecube game)
None of this really screams major support or something that is taking games from Switch.
Well, you'll note that I never used the term "major support", I wrote "fairly big amount of in-house developer attention". As in; they shouldn't be bothering at all with the 3DS now and focus all their energy on the Switch. For me, 2018 is looking like a drab year as a Switch owner. Then again, I never cared about Pokemon or the Smash series, so that's partly up to my taste as well. Overall, 2018 is looking like a pretty boring year for gaming in general. Besides RDR2 and Pillars of Eternity 2, there isn't much on my radar at all if I'm honest.