Nintendo is definitely more hesitant when it comes to broadening their horizons after the complete failure that was the Wii U. Understandably so; regrouping and coming out with commercial powerhouses like BotW and Odyssey was well worth their time. It's just that, we don't really see the Nintendo magic in games anymore, save a few titles like Smash, BotW, and Odyssey.
First and foremost, reviving Paper Mario and Mario and Luigi with proper games. No remakes, no "Sticker Star" approach, just branch off of what made them successful the first time around. Maybe bring back fan favorites like Fawful, the Shroobs, or *ehem* GENO just for an extra splash of creativity.
Secondly, reviving old series. Nintendo is becoming increasingly selective with titles they plan on keeping alive, and even more so with titles they plan on keeping half-decent @StarFoxZero. Anyway, maybe don't pump out so many Mario Party games and make things like, oh I don't know, a sequel to Kid Icarus: Uprising. It sold a commendable amount of units (1.24 million) and the game only suffered from mildly frustrating controls at times. Wario Land is another series that sort of got tossed in the trash; I understand their reluctance on this one since not many of the games sold well, but retouching the games to give it a more Mario-like feel or even a never-before-seen Wario aesthetic in maybe a 3d game would undoubtedly catch people's eye. Golden Sun would also work well, but I think it'd mainly work with an Isaac reveal for Smash. Advance Wars would also be
Onto more recognizable titles, the fourth installments for Pikmin and Metroid Prime are where exactly? I know this year is massively hyped up since it has heavy hitters like Animal Crossing, Pokemon, and Luigi's Mansion that always make a profit, but that doesn't mean other series should be deprioritized. Open world games that Nintendo makes are showing a lot of promise, so Pikmin 4 has a bright future ahead of it unless it goes a route completely unexpected and terrible. Metroid Prime 4 certainly seems interesting with Sylux being the main villain (allegedly) so I hope that doesn't bomb like Samus Returns and Federation Force.
I want to dedicate a section to Fatal Frame. I don't know much about the series, but the fact that two of its installments are often considered among the greatest horror games ever definitely says the series should wait 5 years for the next installment (we're nearing 5 since the last one). I have absolutely no clue why Nintendo went for this IP out of all the ones in existence, but at least do something with it.
The Switch was played out to be the second coming of the Wii. It's popular, no doubt, but as it turns out, the Wii's sales are nearly 5 times that of the Switch. So here we are again with Nintendo playing it safe.