No, I think it's becoming clear the X and Pro models for XBox One and PS4 are industry changing additions. And I doubt Nintendo ignores that trend. 

We're seeing consoles in year 5 of their cycle when you should start seeing decline, and instead you're actually seeing zero decline and in the case of the XBox, you're seeing actual large uptick in sales. This is like someone coming up with a pill that a 60 year old can take that makes them appear like they're in their late 30s again ... that's not a small deal in the business of gaming. 

You will get your smaller/slimmer/moderate bump/different screen size Switch sure ... but the "Pro" equivalent to Switch is also (seperately) gonna happen too. And I'm not talking New 3DS. The XBox One S is basically the "New 3DS" of XBox One models, the XBox One X however is a different beast entirely, and it is what is primarily responsible for XBox One sales remaining not only steady but rising up. 

What Sony/MS have done with the Pro and X models is going to forever change the console industry. This is not a minor thing. 

Personally I think Nintendo is done with the old generational definition you have, so I think that's your hold up there is you can't imagine anything different. But PC has been doing this for 30 years, there is no "generational shift", games come as they please, and developers know full well a higher end game will initially only be available to certain portion of the overall PC base because not everyone is going to have the newest GPU. It's not that big of a deal. 

I know some people think the world would end or something if a console system adopted something similar, but it really wouldn't, it's just different, but people have problems grasping that. The minute you show them a 30 second trailer with an official product most of the time they end up going "I don't want that, that sounds terribl -- oh wait ... that looks kinda hot, I actually might buy that ... oh wow ... where do I preorder?".

For home consoles yes, but what you fail to see is that Nintendo was already doing similar thing with DS and 3DS, DSi and New 3DS are also like some kind of mid gen upgrade, and with point that Switch is essentially handheld hardware, we could expect Nintendo will do something similar with Switch in any case and regardless PS4/XB1.

And Nintendo was very clear about how they want that Switch has longer life span than typical 6 years, but Nintendo already doing that with 3DS, 3DS was launch in March 2011. and in 3 months 3DS will be 8 full years on market.

New or Pro Switch will happen, but difference will be more similar to New 3DS than to PS4 Pro or especially Xbox One X. It point about context, point if PS4 pro is to offer 1440p resolution that could be upscaled to 4K TVs, point of Xbox One X is to offer native 4K resolution for 4K TVs for most of current gen games, while point of New/Pro Switch will most likely be little higher clocks and maybe memory bandwidth that will allow them to have higher resolution with games that have dynamic resolution and more stable frame rate, same like probably better battery life. No Xbox One S is not New 3DS, only improvement that S has is with GPU where clockspeed was raise from 853MHz to 914MHz, while New 3DS recived huge upgrade in CPU (double cores and much higher clocks), double amount of RAM memory and much more VRAM memory. Yeah, Xbox X is totally different beast, but point of that beast is 4K gaming, and that's reason why its selling so better, because 4K TVs are becoming mainstream and Xbox X is best 4K console, but that's totally different context to Switch, Switch is already in any case best and strongest handheld/hybrid (actually only handheld or hybrid, 3DS will be dead next year).

It will, but for home consoles, like wrote, you fail to see is that Nintendo was already doing similar thing with DS and 3DS, DSi and New 3DS are also like some kind of mid gen upgrade, and with point that Switch is essentially handheld hardware, we could expect Nintendo will do something similar with Switch in any case and regardless PS4/XB1.

Generational definition I talking about is not old, look just how much revisions only 3DS has and how long life span 3DS has, Nintendo definitely plans to do something similar with Switch.

Remember, Nintendo was talking about iOS or Android platforms like example for their next platform ("NX" that become Switch), where you have family of devices that are all part of one platform and all games running on all devices, and that's basically 3DS family also become. You keep bringing examples like PS4 Pro/Xbox X and iPad or Samsung tablets, but you ignoring fact that all games for those platforms works on every versions of those hardwares and in same time you talking about big number of big 3rd party exclusive games that would run only Switch Pro version only.

What I personally expecting from Switch revisions is that we will have:

-New (or less possible that name would be Pro, why would Nintendo used Sony naming when Nintendo has couple of its own for improved hardware) Switch that will have improved GPU/CPU clocks, maybe higher memory bandwidth and maybe even less possible more RAM memory, that would alow Switch to have higher resolution and better frame rate for games that cant hit 720p resolution in portable and that cant hit 1080p docked mode with better frame rate and maybe better battery life.

-Switch Pocket/Mini that would be low price option and handheld focused Switch, for instance around 5" screen and built in controls, just for handheld play.

-Switch TV is also possible, similar like Vita TV, It would essentially be just Switch hardware built in similar looking device like Dock (just smaller) of course without screen, battery, parts needed for handheld play, Joy Cons, Joy Con Grip...so basically just Switch SoC built in Dock and shipped with Pro Controller instead of Joycons (but it would have support for JoyCons).

-After that maybe we could have another upgrade for Switch.

Point of all those revisions is they all would support of around 99% Switch library of games, I mean you will always have few examples that wouldnt run on some revisions, I mean thats case even with 3DS/2DS.

After that we will have Switch 2, its very possible that Switch 2 games will be still be cross gen with Switch 1, offcourse on Switch 2 will look and run better.