When Nintendo first spilled more details on the Switch at it's January Presentation 2 years ago, they described it's hardware as all of Nintendo's previous systems rolled into one. The Famicom's two controllers and suite of peripherals, Game Boy's portability, SNES' diamond buttons and shoulder buttons, N64's analog stick, rumble, and built-in 4 player support, GameCube's handle and Game Boy Player, DS' touch screen and wireless features, Wii's motion controls, and Wii U GamePad's off-tv concept.

Looking at the Switch hardware, you can definitely see different parts of Nintendo's past littered throughout its design, even from their pre-gaming products. From what we've seen so far however, I feel like this philosophy can also be applied to the entire first party library of the Switch. Nintendo's software lineup at the moment really does feel like the best parts of Nintendo's different eras on one console. The side-scrollers of the NES and Game Boy, the creative new IP, genre diversity, and polish of the SNES, the ambition and multiplayer focus of the N64, the risk-taking of the GameCube, the casual games, unique controls, and user-friendliness of the DS and Wii, and the ports and DLC of the 3DS and Wii U era. And that's just the first 2 years of the system. If this is what Nintendo can do in that time, then it bodes well for the future of the Switch, especially now with only one main platform to support.

I feel like the Switch first party wise, could possibly be Nintendo's Ultimate era. Taking all the best parts of the past, and refining them to a T.

Oh wait, software wise? Yeah, no. At least it hasn't shown it yet. Maybe after 2019 it will be.

It could be, but for a limited period of time. The question is how many compromises are customers willing to deal with to justify this platform over the other? Even if new SKU is twice as powerful (in that case it might just reach 8th gen home console level, in terms of raw power), and even if all major 3rd party devs jump on Switch bandwagon, this will only last for 2, maybe 3 years as the 9th gen is right behind the corner.

Yes and no.

It's true that it has one of the best Zeldas (originally a Wii U game; not a native Switch game), Smash and Mario games, but the rest isn't that much better or it's just a port.
Splatoon 2 isn't that different from the first. At least from the point of view of someone who hasn't played the second, i look at it and i really can't tell the difference.
MK8 Deluxe is a port.
DK is also a port.
Other franchises like Kirby and Mario Tennis... haven't seen anyone claiming it to be the best of the respective franchise.

New IPs.
There's nothing major, either.
1-2-Switch and Arms have done well, but not to a point where you can forsee them having future iterations in the years to come.

Overall, Switch has been unique in it's own way: it came out on time to get the new Zelda and a few meaningful ports; it has a Mario game that is just like people wanted; new franchises; it will, for the first time, introduce a mainline Pokémon game to the home console front; a return of fan favourites (MPrime and Luigi's Mansion)...
I think it will be really, really well remembered as a great Nintendo system.

They have already given us a masterpiece with Zelda and the best 3D Mario, and i think a sequel is a lock for both. Add to that games like Xenoblade, Pokemon, Splatoon, Smash Bros and future games like Luigi's Mansion 3, Pikmin 4(will never give up), Daemon X Machina and an array of unannounced games they will announce in the next few years there is a huge chance Switch will be the ultimate 1st party machine

Anyone claiming that Odyssey is the best 3d Mario is lying, however the sales are nice

Best Zelda
Tied for best 3D Mario
Best Smash Bros (going by what people say. Personally I dislike Smash)
Best Mario Tennis since GBA/Gamecube days
Best Mario Party since the Hudson Soft games
Best Mariokart
Lackluster Kirby
Lackluster Pokemon
On the whole, most of these franchises have either had one of their best games yet (Zelda, Mariokart, 3D Mario), and some have had their best entry in a long time, going towards the right direction (Mario Party, Tennis). Only Kirby has been somewhat disappointing. And I'm not worried about pokemon because the next one wont be a cash grab like the one we just had.

Cant speak to Xenoblade cause I dont play JRPGS.

Yeah I think the Switch has a great chance to host Nintendo’s best collection of first-party games on a single console. It’s made great strides toward that goal in 22 months.

The system will need a second Zelda/Mario for sure though.

If you think support for this console will last only 2 or 3 years due to new systems releasing in 2020, you're in for a surprise. This will neither stop Nintendo releasing new games on it, nor it from keep selling well. By the point the new machines launch ($400~$500), Switch will most likely be around $200, half the price, so it won't be really competing with them. I also expect exclusive third parties to keep releasing on it, especially Japanese ones, as it has no competition there. Btw, Nintendo commented on how they want this cycle to last longer...

OT: I'm starting to agree with this logic. If all goes down well enough, it will end up being the best Nintendo console first party-wise.

Likely tbh as when you look at whats out and whats on the way and what could come after that it could very well end up as their best platform for first party titles to date.

Currently out/Announced:

NSMBU
BOTW
SMO
MK8D
Splatoon 2
DKCTF
Yoshi CC
Xenoblade Chronicles 2
Mario Party
Mario Tennis
Smash Ultimate
Pokemon LG
Bayonetta 3
Pokemon Gen 8
Animal Crossing
Fire Emblem Three Houses
Luigi's Mansion
Metroid Prime 4
Retro's Project
Monolith's Project
Arms

Possible Future Titles:

Pokemon Gen 9 or/and Remake
Mario and Luigi RPG
Paper Mario
Tomodachi
Zelda Switch
Pikmin