But the hardware already made profit way back in 2017, of course they couldn't justify increasing the price.

It's very old hardware at this point, unlike PS5 and XSX.

It may be old hardware, but not much of that hardware actually got much cheaper over time, and many parts are actually more expensive to source nowadays as they were 7 years ago.

Keep in mind that most consoles got cheaper not just due to cost of electronics dropping, but mainly because those consoles have a reduced set of hardware compared to the earlier iterations. That's something that won't really happen this gen for any of the 3 consoles, hence why neither will have any price drops this gen and instead the prices are going up, as the "slimmer" PS5 showcases.

I'm sure Nintendo is making a boatload of money on every Switch sold these days. They were making good profit 6.5 years ago when it came out, that tech is now ancient and likely extremely cheap, and while there may still be a bit of an issue with chip shortages I'm pretty sure it's mostly abated compared to a year ago so those prices have likely come back down. Sure we aren't in the days anymore when a company can knock a system from $300 down to $99/$150 over the course of its lifetime, but they gotta be making a ton of money on every system sold at this point. No price cuts on Switch have been due to its popularity not requiring price cuts, not because of profit margins.

How many units do we expect it to sell after Switch 2 launch? I think somewhere between 10 and 15 million units.

10-15mil is certainly a stretch, seeing how PS4, Xbox One, and Wii U performed following the release of their respective successors. Unless Nintendo intends on support Switch well into the successors lifetime similar to what they did for the 3DS, I don't think this is possible. 3DS barely pulled this off even with an original, mainline Pokémon and Metroid title.

My LTD projection would be 141mil by end of the fiscal year (ending March 31, 2024). Switch will run through 2mil and >1mil in the first two quarters of F'24, it will experience its last big quarter with 4mil in the holiday season of 2024, and 2025 will essentially be the end (~4mil for F'25). Under this trajectory, the Switch should be neck-and-neck with the DS, though PS2 is a little bit unrealistic if Nintendo drops support. If they continue support or push the successor another year, then it will be an easy sweep for the Switch...at the expense of the success of its successor.

Kep in mind that Sony supported PS4 for several years by making their first party games cross-platform, until just now I believe with Spider-Man 2?
God of War Ragnarok was cross-platform, and so was Horizon Forbidden West and Gran Turismo 7.

And still to this day almost all third party titles are for both PS5 and PS4.

Despite all that, and the fact that you could barely get a hold of PS5 for a few years due to the global chip shortage, PS4 still didn't sell much after PS5 was released.

Wasn't because Sony drastically cut PS4 production despite its longevity potential expected for sony consoles?

There's no increase in Europe for both models, the Digital is getting a price increase in the US (don't know why) but the disc will be the same price.

I can understand the increases in Japan due to the low yen exchange, they shouldn't have done it, but they did it anyway.

As for the Switch, 7 years in and no price cut, don't know why people are still expecting a price cut when the entry level Switch is $199.

I don't remember.
But considering the chip shortage, they probably produced way fewer of those as well.

Depends on a few scenarios and how many Switch consoles Nintendo manufactures.

1. Switch 2 is either too expensive, lacking games, or an unappealing concept. So, pretty much some version of the Wii U situation (but almost no chance it's that severe). In this scenario, customers will still see a lot of value in Switch (even if it too is partly hurt in branding). We're talking about anywhere between 12-25 million units if Switch stays the same price or gets a more modest price cut. Aggressive price cuts in this scenario would likely lead to about 22-32 million units sold post-Switch 2 launch.

2. Switch 2 is as successful as Wii right out the gate. Nintendo will still make and sell some Switch consoles but will greatly reduce manufacturing to focus on Switch 2. We're looking at about 4-10 million units in this situation. 

3. Switch 2 is successful or really successful and Nintendo still wants to milk Switch for as long as they can. We're looking at about 9-15 million units in this situation. 

Scenario 2 is the most likely, followed by 3, then 1. 

I've been wrong about Switch and Nintendo many times. But there has to be some saturation point for Switch. If Switch is already at 150 million units or higher by time Switch 2 is out, I don't see a reasonable ceiling for Switch above 175 million. And that's a big ask as well. And 200 million or above is highly improbable. Consumers would have to really want Switch in lieu of Switch 2 and Nintendo would have to make them super cheap.