Go out of their way to make something that can't be done in Mario maker. Hand drawn art or hight quality 32bit style sprites, set pieces like dkc tropical freeze, more unique bosses, massive shake up of level themes. Or hell maybe even stop doing 2d entirely and keep the 3d world/land style going with more fully 2d  levels thrown in 

Interesting, would be cool if they did this, and included a Mario Maker mode for it. Or hell, make Mario Maker 2, and have what you described be an included single player Nintendo designed campaign to go with a new option to group levels into worlds and campaigns, with a way to make custom world maps.

Oh yes the port will absolutely be $60. I was absolutely shocked when the did it for DK but since they did that there is no way NSBM U port won't be $60.

Other than Mario Kart they really should have made a policy than any Wii U ports will be $40. If they did that I don't think anyone would have any problem with Nintendo porting a bunch of Wii U games, as long as they were being ported at the same time as new games in those franchises are being developed for Switch. Releasing Wii U games at $60 tells me Nintendo considers them new games for the Switch and can therefore take the place of an actual new game in the franchise. Like since they released DK at $60 (more expensive than it cost originally!) I know there won't be a DK game on Switch for years. With a likely $60 NSMB port on Switch in 2019, when I had been expecting a new 2D Mario game in 2019, I now expect to not see a new 2D Mario game for a few years. I don't know what the hell Nintendo is doing with all their resources since they should be focused on a single system for the first time ever basically, but it seems they are diverting their resources to bring out full priced ports instead of new games.

As someone who used to own a Wii U and sold it to get the Switch, I'm starting to get a bit annoyed at all these ports. I mean, I don't have a problem with the ports themselves, I even bought Bayo 1 and 2 again since I liked them so much (And I'd buy WW+TPHD day one on the Switch), but most of them shouldn't be priced as a brand-new game would.

I get why they're doing it, but it's hard to be excited to play the Switch when so much of its first-party library so far has been old stuff. Ports aren't bad when released alongside new games, but so far they've just been used as replacement for new games. I'd love a new 3D Donkey Kong for example, but Tropical Freeze might as well be the DK game on Switch, who knows if we'll get a new one in the coming years (Be it 2D or 3D).

I love the Switch's hardware and it's so much better than the Wii U, but I can't deny that I'm disappointed with the line-up for the time being. At least 2019 sounds like it will be great, and Smash looks amazing too.

Kill it with fire!!

I was thinking about new playable characters. I definitely like the idea of Daisy, and Super Mario Run means she's possible. Super Mario 64 DS had Wario and had Yoshi directly playable, so that's possible as well. It might be fun to have characters that unlock throughout the journey as you save them, that let you revisit old levels and find new exits with their new abilities. Anything to make the game feel like a journey like Super Mario World did instead of just 8 sets of levels and a Bowser fight like pretty much every NSMB game and even 3D Land and 3D World did.

Instead of E. Gadd being playable though, I'd thought it'd be cooler if he were a side character that made wearable, game-changing gadgets like he did in Sunshine and Luigi's Mansion, except on a per level basis instead of something you wear for the whole game. Remember how having Yoshi as a mount in SMW was a huge game changer, in that it introduced a fundamentally new game mechanic never before seen in a Mario game? The gadgets would be a way to have that feeling again. 2D Mario hasn't gotten anything like that since then. Just more powerups, but every game has new powerups. Yoshi as a mount was kind of like a powerup, but he was fundamentally different from the consumable item powerups. The E. Gadd gadgets would be like Yoshi in that way, adding a fundamentally new game mechanic. Maybe all the stars they've been hiding in 2D Mario levels lately unlock new gadgets, which allow you to revisit old levels for new paths and exits. Between that and new character abilities, and a secret world like Star World, you could create a much more memorable game than any of the NSMB games.

Either Mario Maker 2, or something more akin to Super Mario World. New Super Mario Bros is dead, leaving aside ports of course.

I really liked the Wii U version. It was actually the best of the 3 NSMB games i played (didn't play the 3DS game).
But when i tried to play it a second time, it was really hard for me to play it again. On the other hand, i had a blast replaying Mario 3D World.

The style of the game is just unnatractive. It really, REALLY needs a full overhaul.

There's a few things Nintendo can try:
They can go back to the 16-bit style - as in, go retro; they can also really make something new: forget playing with adult Mario, give me a teen like Mario and Luigi in a more stylised world.

Using a more kid/teen Mario would be something that Nintendo hasn't tried and it could help set the ambience for a different attitude for all characters, to give the story more relevance and also the relationship between Mario and Peach.

The idea of Teen Mario just makes me think of Sonic the Hedgehog, which makes me think of this video:

https://www.youtube.com/watch?v=2tEJgS3Y3hE

Not that kind of teen Mario! That's for sure. :D

Really, just you usual Mario but with more "spirit".

The story: Bowser uses a time machine to try and defeat Mario, Luigi and friends in their past (weaker selfs) and starts the endless story of kidnapped Peach. The adventure of a lifetime! :D