Part of my problem with the "we don't have leaks, so it can't be released this year" line of thinking is that by the same logic Nintendo isn't going to release a single game after Pikmin 4 this year.
Most of the leaks we get about new hardware from gaming media and "insiders" comes via developers. Journalist talks to developer, developer says "Hey, I'm working on game X for the new hardware, here are some details". Good journalists talk to several developers before publishing, not so good journalists just publish straight away with one source. The fact that they're dealing with developers means they have to know about game X, and probably games Y and Z if they want to do a good job getting multiple sources. That is, for journalists to know anything about unannounced hardware, by necessity they must also know about unannounced software as well.
So, what unannounced Switch games have been leaked by reliable sources? We have Twilight Princess and Wind Waker ports, which leaked a long time back, would appear to have been sitting on a shelf for a while, and are very unlikely to release this year, given the game that released last week. Outside of those, I'm not aware of a single game which has been leaked by reliable outlets. I've seen people referring to Paper Mario TTYD and F-Zero GX ports/remasters in this thread, but in the former case it's based purely on a random Famiboards poster, and in the latter case the thread was locked here for lack of evidence. Ports and remasters are also exactly the kind of thing fake leakers will go for, as they're a much safer bet than trying to come up with the details for a fake new game.
I'm also not aware of any unannounced third party games which have been reliably leaked. Dusk Golem talked about a Switch Resident Evil game, but that was supposed to be released a year ago and I don't think we've heard anything about it in two years. There may be something else I'm missing, but I had a look back through the "Rumour" threads here and didn't see anything.
So, as I see it, either Switch will have an exceptionally quiet second half of the year, or the developers of unannounced Switch games aren't talking to journalists. The former I don't see happening, regardless of any new hardware, as the lineup for the first half of the year has been very strong, and had there been nothing to release in H2, Nintendo could have easily pushed back several titles. That leaves Switch developers not talking to journalists, and if they're not talking to journalists about their games, they're hardly talking to journalists about new hardware.