I would've laughed at you. I thought NES on the lower end to 3DS on the higher end. 

Now I don't laugh at people that would say it could sell PS4 numbers. Because even though I don't think that will happen, it's possible. I do laugh at those who say it can reach DS or PS2 levels because those platforms were truly lightning in a bottle. If I'm proven wrong, I'll be shocked.

I want to believe!

I don't think so. For this to happen there would need to be a major revision, and at that point, I don't think it would make sense to consider them the same system.

It all depends on Nintendo to be honest. If Nintendo really wants this system to have a longer console life than their previous consoles then yes. If Nintendo in 2-3 years launches a new system then no.

We need to remember
- There will still be at least another revision
- There will be price drops

Also, remember the switch has yet to hit the sweet spot which is $130 dollars.

Of course not. Still remains to be seen if SW will even match the PS1, GB and PS4, let alone the PS2 and DS.

I certainly think it has the (realistic) potential to be the 3rd best selling - after the DS and PS2.

To be the first isn't impossible, but Nintendo would have to support it for at least 4-5 more years, release more quality exclusives, and probably crank out another new model or 2 + a few price drops. Basically, they'd have to do a LOT right to get the number one spot. 

More like 130-140 million. But yes i agree.

There is no way in hell it does not beat PS1 lol and even Gameboy is the absolutely worst scenario.

In what scenario does it not beat the PS1? Especially when it's pretty much neck and neck with the Wii.

PS1 - 102.50 million
Wii - 101.64 million 
NSW - 55.77 million (As of March 31st.)

And that's after Nintendo reported 21.03 million units shipped for the FY 2019. And so far FY 2020 is looking like it will pass that number without even trying.

Switch Yearly Sales:
Week 30 - 2019: 6,741,282 
Week 30 - 2020: 11,663,173

Right now, it's a whopping 5 MILLION UNITS ahead of last year's total at this point in time. IF Switch sales for the rest of the fiscal year are completely flat/dead even with last year, that would put Nintendo's shipments at 26.03 million units, which would surpass the Wii's peak year (25.94 million units in FY 2008). That would bring its total sales to 81.80 million units by March 31st, 2021 - the end of this fiscal year. From there, it would only need another 20.71 million units for the rest of its life span to pass the PS1.

So again I ask, in what scenario does it NOT even match the PS1? Its sales would have to crash, burn, and explode faster than a tank truck colliding with a gas station on the freeway for that to happen.

It is possible but to achieve that level of sales you need to push for it.
Switch still has no price cut so it shows they will probably keep the console going for a long time.
We also can see, atleast in japan, that the Switch lite, although less expensive, is really far from being as attractive as the hybrid Switch. So a price cut has the potential to drive a lot of sales. Mainly knowing Nintendo's appeal is quite large and touch families and casual gamers more easily than others.
They could also release a new upgraded model. I feel like the pandemic will keep helping the gaming industry like in past recessions. I do think the Switch will have the advantage tho for being less expensive.
Predictions keep going up every year. We said 100 millions last year and now most expect 120 millions. I'm sure next year it might be more.
Nintendo keeps on surprising us with the Switch and i'm excited for what's coming later. But it will all come down to what the goal is for it. Will they profit of the Switch while it last since they have only one system or will they launch another one quickly by fear they will lose money if the sales go down too much ?

We'll see, atleast they don't have competition in the hybrid/market departement so we shouldn't see another GB/DS scenario. The Switch also doesn't feel as dated as the Wii did in the HD era, which was quickly rejected by the casual crowd.