This is exactly the sort of thing I’d like to see as well, and that’s part of the benefit for using the architecture they are. It seems like a big waste if they don’t pursue this route. The only thing I’d change from your post is the timeframe between iterations, which I think would be best at the 2 year mark and 4 years retail shelf life; still with 6 year support.

Nintendo will just have a more powerful Switch with a bit more changes to the system. Thing is that Nintendo likes to do things as a cycle. It goes invent the wheel --> update the wheel --- > reinvent the wheel --- > update the wheel. Anyway here are some examples I am talking about.

NES --> SNES
Gameboy ---> GBA
DS ---> 3DS
N64 ---> GC
Wii ----> Wii U
Switch ---> Nintendo Console hybrid 2
Right now we are in the reinvent the wheel stage. Nintendo is very predictable in their hardware at this stage. Don't expect a new Nintendo hardware until at earliest 2023. Latest is probably 2024. They need 1st party software to push the system and that software won't be ready until 2023 or 2024. Nintendo might even release it in 2025 to avoid a repeat of 2018 Switch software-like problems but we won't know for sure since that is years from now.

By far the most important thing for me:
Keep the wireless seperated controller. Some kind of WiiMote and Nunchuck or the Joycons has become a MUST for me. I can not play with an regular gamepad anymore. It is just a pain for me, the Joycons are sooooooooooo much more comfortable. I never want to miss them again. I dont really need them for motion control, but I need them to have both arms independend from each other.
But they need to make the Joycons much better. The connection range is really shitty sometimes. When there are some obstacles like a couch and a pillow the range goes down to not even 1 meter - when I moved some furniture I really had a problem with that. That was really annoying.

Other than that I dont really care what their next system will be.

Switch U

The Wii was basically a more powerful gamecube with minor changes and the Wii U was basically a more powerful Wii. Wii U even uses Wiimotes to play multiplat games, and can even run Gamecube games. For 3 generations, Nintendo released nearly the same console over and over.

And so was the Gameboy Advance, then the DS and then the 3DS.

So, it is wrong to say "It's Nintendo so it won't happen" cause Nintendo did it several times.

New Switch every 2-3 years, best mobile chip Nintendo can get every time out.

Old model is supported for as long as its feasible.

No "new generation" nonsense, just one continuing generation basically, much like PC ... where are the generational breaks in PC gaming? There are none, you just buy a new GPU when you are ready.

Nintendo will make more money this way and ultimately while a small minority will complain, the majority of the consumer base will enjoy the new setup.

Waiting until 2022/23 to upgrade the current model in a meaningful way is stupid, all that's going to happen is Nintendo will lose all momentum they have now and the hardware will become badly out dated and non-desirable. The Switch is not a casual platform like the Wii, nor is it a kiddie budget machine like the Game Boy was where the hardware doesn't really matter. It has to be relevant on a technology level for the "it's a home console + portable" aspect to work, if its too far outdated as a home console the whole appeal of it falls apart and its just an oversized Game Boy with a TV output. 

That's something the has limited appeal. 

Are you serious ? Everyone knows that. Even Miyamoto said it: 

https://gizmodo.com/205275/miyamoto-says-the-wii-is-basically-a-gamecube

"‘The hardware is basically a GC. We’ve upgraded our development tools to new versions but, you can still use GC programs as they are. With that in mind, I thought we could remake GC titles for the Wii and modify them to work with the Wii remote so that they’re more fun to play.’

So everyone here is in agreement that generations need to die and iterations need to reign supreme. So a switch version 2.0 and version 3.9 etc but the previous versions are supported until it's not viable. So like support switch alpha until 3.0 and switch beta until 4.0 etc. Maybe have half refreshers like 1.5. Hey that's a great naming scheme in Greek alphabet. But anyways I would love that but also they need to keep updating the joycons as they go on and the newer joycons are supported with old hardware as well. And then you can still play every game from switch on every newest model. Make something like iOS and call it the shittiest name they can think of but still have a basic OS for all switches that keeps updating. No need for backwards compatibility shenanigans or anything like that. Develop the VC as a separate service where you pay something like 60 a year but can play games upto and including the Wii or eventually the Wii U or something. Have every console represented so in a way make a system that has all of Nintendo in it. That sounds awesome but doubt ninty will do that. They aren't that happy to change and console generations is like a tradition to them and they love their traditions

That's just it. We compare the 3DS against other mobile platforms... And in such comparisons, the 3DS doesn't seem as nearly as dated.
Same should go for the Switch.

...But once you start pitting it against the Xbox One/Playstation 4/PC, then its' limitations quickly becomes apparent... And that is perfectly fine.

I disagree. The human eye doesn't see in terms of pixels anyway.
1440P just looks significantly sharper... My phones for the last 3-4 years have all had 5.7" 1440P displays or better... And the resolution uptick is certainly noticeable over 1080P, especially when it comes to HUDs/Text.

My phone with it's 2960x1440 display gets better battery life than the Switch when playing Fortnite.
The displays inherent technology can have just as big influence on battery life than the resolution of the display itself.

In-fact when Samsung increased it's phones displays from 1080P to 1440P in it's mainline Galaxy devices they also had an increase in battery life. Why? Because the newer display technology was more efficient.

Completely disagree.

However... If you really wish to go down that rabbit hole... There are plenty of cheap crappy chinese tablets on the market with 1080P IPS displays, clearly price isn't the issue.

With that said, you don't need the GPU or CPU power to render games natively at the displays resolution to see the benefits of a higher resolution display... To me, 720P is obsolete, it shouldn't even be a thing as we enter into 2019, not even on a $150 netbook.
1080P is low-end... And 1440P should be the baseline.

4k Textures were in some 7th gen games. (As in 4096x4096). That is despite most games only operating at 1280x720 output resolution or lower, texture resolution isn't 1:1 with display resolution.

Compression allows textures to take up a fraction of the space... Current 8th gen titles seem to be spending a ton of storage budget on uncompressed 7.1 Audio.

The Wii was it's own console because of it's controller. If the PS4 is different from PS3 because of more powerful hardware, the Wii is different from GC due to the controller. And DS is certainly not GBA. And the Wii U internally was very different from Wii.