So we got Zelda BOTW, Mario Kart 8, Super Mario O. and Splatoon 2 seemingly selling till the end of time.

But ever since SMO we didn’t get another such title for the Switch.

When and Who do you think will be the next Switch’s evergreen title?

Super Mario Party and Smash

Pokemon Let’s Go....anybody?

SMP/Smash/Pokemon
2d Mario the rumours are true

Kirby will continue to sell for a long time, even if not in the same pace as others.

But the obvious answer is Smash.

Kirby will only last a year in the charts, not bad, but not evergreen. Super Mario Party will be the same way. Both will do respectable numbers for their franchises. People I think undercount Pokemon Let's Go a bit, but I agree that being a semi-spinoff reboot of Gen 1 released a year before Pokemon gets its first mainline (sort of) home console entry means that its legs will be cut short. Smash will sell until the next Nintendo console releases and maybe even beyond that, so it's the next evergreen game. Beyond that, 2D Mario might happen, but a NSMB port won't do the trick unless it ports every NSMB game together. Animal Crossing would almost certainly do the trick, seeing as New Leaf is STILL selling and appearing in charts to this day. Beyond that, a new Mario Kart, an Odyssey or BotW sequel, or a new IP altogether are Nintendo's best bets for further evergreens unless Metroid Prime takes off like it fucking deserves to never has before.

If by blue ocean ypu mean a title that tries to appeal to the highest amount of people possible, 2D Mario would be fairly safe. Mario Maker would follow suit. Another Pokemon spinoff might be coming too (we've had surprisingly little Pokemon on the Switch).

The next one? Super Mario Party, which will drop on early October, so we're still a full month away. After that, Pokémon could become one, and Smash certainly will.

Obviously the next one is Smash. Seems bizarre people are mentioning mario party. I'm sure that it will sell a few million but its not gonna still be selling years from now, heck there will I'm sure be at least one more mario party on Switch later on to replace it. Pokemon Let's Go will sell very well but as a side game it won't be evergreen and its sales will likely plummet within a year since the real Pokemon is coming next year.

So just Smash for 2018.

2019 will be Animal Crossing if it hits that year, obviously Pokemon, and I would have said 2D Mario but a port will not suffice.

Call me crazy, but I think Super Mario Party will be a breakthrough for the franchise. Mario Party 8 on the Wii sold 8.85 million units, more than games like DKC returns and Zelda Twilight Princess (Wii), so the potential is definitely there. As long as they don't follow up with a sequel very soon after, though.
Other than that, it's Smash, Animal Crossing, Pokemon 2019, and a follow ups to Mario Odyssey, and Breath of the Wild.