I think that you hit the nail on the head.

If Nintendo ends up releasing a Switch Pro that has all the bells and whistles that we are hoping for such as DLSS and a significantly improved screen, then there is no question that 150M will be easily passed by the Switch and I even believe that 200M is realistic target.  That bigger question we need to ask as a community in this case, though, is whether this counts as a new console or is a refresh similar to what the New 3DS was.  Is backwards compatibility and a similar name and form factor enough to consider two pieces of hardware to be the same console generation even if the hardware capabilities are radically different?  The New3DS was not that much faster than the 3DS and a lot of people who had a 3DS did not re-purchase a New 3DS, but if the Switch Pro ends up using DLSS and is capable of 4K resolution then this puts it in new generation ballpark and a lot of people are going to want to have both models.

The question here comes down to a logistical one.  The momentum that the Switch currently has will land it somewhere close to 150M assuming that Nintendo does absolutely nothing in terms of hardware releases over the next 5 years, but this is highly unlikely in my opinion.  If Nintendo releases a vastly improved Switch pro in the next 1-2 years, then this will decimate the original Switch sales (maybe it peaks at 110-130M) but the new model is probably going to explode, especially if it is good as the rumors are suggesting right now.  In this case, it will come down to whether we consider the new Switch model a part of the original Switch generation.  In my opinion, if a ton of people are rebuying the Switch Pro for the radical enhancements it has then it doesn't seem fair to Microsoft and Sony in the console wars to continue adding up Switch sales.

Shoot, I didn't think about that. When you consider everything that's going on Microsoft could actually be trying to merge with Nintendo. Keyword merge. I'm sure if Nintendo would be bought they'd wanna have their name in the new company that would actually be beneficial for Microsoft too. The new company would be called Microsoft-Nintendo. I don't think this merger would go through with authorities though. It would be too powerful in the Videogame space. Now a partnership where Nintendo games Come to Xbox/Pc and Xbox games to Nintendo. That would be something I'd like to see. Imagine Botw 2 on Pc with Rtx on+hdr that would actually get me to upgrade my Graphics card as soon as possible.

Damn, what info do you have that everyone else is missing? I'm not confident either way, but you must have knowledge that everyone else doesn't.

Probably not. It's not impossible (yet), and I would be pleasantly surprised if it did, but I doubt it will happen. Personally, I'm thinking it'll end up somewhere in the 130-140M range.

First off, the PS2 & DS sold about the same globally, with the DS coming up just short of the PS2 (mainly because of Europe and RoW favoring the PS2; the DS came out on top in the U.S. & Japan). If the Switch can't beat the DS globally, it can't beat the PS2. The Switch is trailing the DS in the U.S., Japan, and especially Europe. The only reason it isn't even deeper in the hole against the DS is because of the pandemic (and a temporary assist from Animal Crossing, which may or may not have also benefited from the pandemic). However, it is exceeding the PS2 in Japan, and will likely pass the PS2 before this year is out. In the U.S., the Switch recently pulled just slightly ahead of the PS2, if we exclude the PS2's launch holiday, but it's also worth pointing out that the PS2 continued to sell very well into the later years of its life (19.4M units from 2005 to 2011), which could limit or, further down the road, potentially eliminate whatever lead the Switch gains over it. However, in Europe the Switch isn't selling anywhere close to what the PS2 sold, and is even trailing the PS4 by a significant margin.

On a regional basis, while the Switch is going to beat the PS2 by a very comfortable margin in Japan, and has a decent shot of beating the PS2 in the U.S., it's not going to get anywhere close to the PS2 in Europe. That European deficit will seriously hurt the Switch's chances of being the new #1 system globally, and I think it will likely completely prevent it from doing so.

Regarding Nintendo trying to extend the generation to maximize Switch sales, they can try, but another hardware revision alone won't cut it. Trying to grow sales through price cuts and/or hardware revisions is an effort that yields diminishing returns over time, regardless of the platform. With systems that have had multiple hardware revisions, the revisions released later on have never had a significant long-term effect, though they do often produce good short-term gains. This will likely be the case with the "Switch Pro," especially if it's a higher-priced, higher-end model (like the PS4 Pro or One X).

Nintendo is going to have to break with over two decades of past behavior and actually give serious, meaningful software support to the Switch for at least the next three years. And I'm not talking about just mid-level titles, spin-offs, and remakes/remasters. I'm talking new, original mega-blockbuster franchise titles. 2022 & 2023 are going to need to be as strong as 2017-2019 were in terms of software lineup. If we see things start to slow down next year, that could be a sign that Nintendo is drawing down support for the Switch in preparation for their next console, which isn't implausible considering their track record.