One strength of Switch that existed in the Wii and DS era are the titles with a longterm appeal. That is games that still sell or help sell the console even years after they released. Mario Kart 8 Deluxe and Breath of the Wild are continuing to draw audiences to the Switch. This is why I think next year, and perhaps even the year after, are going to be bigger years than this year (and at least bigger years than last), ESPECIALLY if Nintendo begins doing multi-game bundles: Switch + Breath of the Wild + Mario Kart 8 DX + New Super Mario Bros U/Mario Maker (The Gen X appeal Bundle) and a Switch + Odyssey + Splatoon 2 + Pokemon (The Millennial appeal Bundle) and perhaps reach out to third parties: Minecraft + Fortnite + Rocket League (Gen Z appeal bundle).
Switch has evergreens, games that keep selling for years. That makes it like DS and Wii. What makes Switch different is the type of evergreens it has. Wii evergreens were things like Wii Sports and Wii Fit. Switch evergreens are things like BotW and Smash Bros. Switch evergreens are for core gamers.
I agree that Switch is going to keep selling because of its evergreens, but what is different is who Switch will be selling to. The Wii and DS brought in a ton of new gamers. Switch will be selling to core gamers though. It is going to bring in PS4 and XB1 customers.
Overall, I liked the Wii, but I like the Switch even more. Since the main customers are core gamers, Switch ends up with a lot more games that I like. And I kind of feel it is still only scratching the surface on the third party side. Mostly we've gotten ports and indie games. I think the third party library is going to improve a lot. Third party companies are realizing that they can sell their core games on the Switch, and that makes it different from the Wii. As the third party library improves that will bring in more customers on top of the Switch evergreens.