Pokémon, Fire Emblem, Metroid & PIKMIN all have been announced for the Switch with a title only. The only common thing that they have is there was a 3DS game as well for each of them (Ultra Sun/Moon, Echoes, Samus Returns, Hey! PIKMIN). I can see why Nintendo may not be interested in showcasing the games early but have to acknowledge that they're in development to prevent blacklash (all of the announcements happened after the Switch Jan conference). Nintendo also doesn't usually have a CG teaser since they tend to highlight gameplay rather than story/VA (I don't remember a recent game having a trailer with no gameplay). Revealing more interesting / fun / impressive gameplay for these games will definitely undermine the 3DS titles too. I think we just have to be patient until the 3DS is not very relevant to Nintendo and doesn't account to a lot of their revenue.