Then they can delve into their lower tier properties and focus on more unique and niche games for 2020 as well.
Not going to help either since Nintendo used many of their lesser IPs already ...
They still have stuff like a new Star Fox, ARMS 2, any 1-2 Switch-esque party games, more Mario Sports, Diamond and Pearl Remakes, Bayo 3, and perhaps more New IP and co-productions with other developers. Nintendo isn't like a tank that can only use a set number of franchises and that's it. There's plenty of avenues they can take for future Switch software.