Yep, this is exactly what I expect but I don’t think it will just be visual upgrades, more like Wii U to Switch ports where each game had added content (some minor like Funky Kong in Tropical Freeze, some substantial like Bowser’s Fury in 3D World).

I'm hoping the Switch 2 supports backwards compatibility with free upgrades that have minor improvements. I'd be happy with more stable framerates and improved resolution. 

No improvements. Some games get substantial full priced upgrades instead.

It’s not right, but it’s ok.

I voted major improvement BC with $1-$10 upgrades.
Nintendo giving free upgrades universally or even as the standard is even more unlikely than boosted performance. Nintendo charges $60 for enhanced Wii U ports for crying out loud.
I don't think the boost will be universal like turning on boost mode on PS5. Nintendo software and third-party game upticks in performance for BC games will almost entirely be at the mercy of the devs in a free update. Unpatched games will probably have marginally better load times and a trifle better resolution and frame rate just from the better hardware without an active boost or update.
The Zelda games and Xenoblade Chronicles series will get updates for sure from Nintendo.

I think with Nintendo, it's not just what the hardware can accomplish with BC, but an organizational philosophy. I think Nintendo's approach is, "Why give away upgrades for free when we can make a little extra cash for it?"

The Switch ports of Wii U games were their own thing due to and complete and total incompatibility plus the Wii U having practically no marketshare so its games were new in most customer's eyes. But remember that Nintendo wanted you to pay for upgrades of your Virtual Console games from Wii to Wii U, and pay full price again for those same games on 3DS VC even when it could easily see that you've already bought said games on two other consoles.

Outside of aforementioned marginal improvements like more stable framerates and consistently higher resolutions, if Nintendo has to go out of the way to make a game available on a new platform, it wants you to pay for its troubles.

Uh, I'd like it to just be normal BC where it's the same game that it was on Switch. And if they do decide to do upgrades, those should be free (which I don't expect Nintendo to do). 

I would expect at least "Switch 1 docked" settings in the undocked mode of the Switch 2. Combined with automatic improvements (more stable fps, less slowdowns, dynamic res in the upper range) that would be a huge improvement for handheld gamers with zero effort / extra costs for Nintendo.

Like flipping a switch.

This one seems pretty obvious. Games with dynamic resolution and unstable framerates will see improvements in those areas due to stronger hardware. Faster load times too, if the speed of the storage medium permits it. Any improvements beyond that will require patches. Whether those patches will require extra payment (or if they even happen in the first place) will be up to the publisher. Some games might get a dedicated "Switch 2" version. Getting that version for free if you own the Switch 1 version is rather unlikely. There is no reason for any publisher to be that generous, especially in the current era of monetization and rising dev costs.

Not true. 

https://youtu.be/bKQ6NeTjccA?si=NDv-tVQni_qRGGB

Sure, PS4 games use the "PS4 Pro" profile on PS5, but they still run much better in both framerates and dynamic resolutions. 

Well, that's what I said, wasn't it? Some games run better, others however are broken and run better in a PS4 Pro instead.

There's a thread in Era compiling all the resolution/framerates of PS4/PS5 games that you can check out for yourself.