Problems with this reasoning.
1) Switch is not an upgrade. 32X and SupergraphX were a lot like the Move and Kinect of Generation 7. All of those are upgrades. Switch is not an upgrade.
2) The "late starters" are all systems that no one cares about. You can put them in any generation you want and no one really cares. They didn't compete against other consoles, because no one really bought them. It's like asking which generation had the Virtual Boy. No one cares.
Switch is already selling like a top-tier console. People care what generation it's in. What systems is it competing against (if any)? That is one type of question that people answer based on how they view generation. In truth, wow a person a categorizes the Switch reveals how they interpret the market place. That is why this is an important question. (Not calling you out on this specifically. I started replying to your post and now I'm just getting up on a soapbox.)
What I have observed is typical for people on this site is that they make predictions, then they are wrong, and then they don't change their assumptions. That is not a terribly scientific way of thinking. (A scientist changes their view when their prediction is wrong. That is how the scientific method works.) People thought the Switch selling 40m lifetime was optimistic. Then the Switch sales showed that was 40m was really very pessimistic. But then people still don't go back and change their assumptions. Why were the predictions so low in the first place? What wrong assumption was that based on? People never ask that, so they keep getting the assumption wrong. (Hint: one very common faulty assumption is never considering the handheld market, and that is one bad assumption of several.)
So that is why getting the Switch's generation right matters. At least it should matter to people who want to actually make accurate predictions.
1. Yes, I know. They are meant as a precedent to PS4 Pro and Xbox One X, not the Switch. I meantioned them because of the timing: They released around the same time those late starter console of the generation came along, just like the Switch arrived when Pro and X got released.
2. So? Did they need to be successful to create a precedent? Nope! Neither did the upgrades of the time btw. But that didn't stop Nintendo to make successful upgrades later on with DSi and New 3DS, and Sony and Microsoft later on, too. A precedent suffices, and that we had with Gen 4. In other words, Switch is Gen 8.
2. They need to be successful enough in order to know which systems they are competing with. The Genesis launched in the US in 1989, two years after the NES went nationwide (1987). We all know that it competed with the SNES regardless of that. These systems have to be significant enough to know what their competitors are. Technically I would probably put, for example, the CDi in generation 5 considering it was a CD based system. But I don't really argue about it, because I don't really care. There is no real way to know which generation it's in because it didn't sell well enough for us to tell.