The Switch 2 will be a large upgrade over the Switch 1. The Nvidia leak basically already confirmed this anyway.
The people who keep trying to bring up past Nintendo generation transitions purposefully are deceitful in how they recount the past and leave out pretty huge details.
For starters, almost every Nintendo system has a had a full generational leap from its predecessor when the time came to upgrade. NES to SNES, SNES to N64, Game Boy to GBA, GBA to DS, DS to 3DS, etc. etc. etc. These are all massive upgrades from their predecessor.
There are only two exceptions, the GameCube to Wii and arguably the Wii U to Switch (though this is tricky because the Switch is the successor to the 3DS just as much and there it is a monstrous upgrade). But in these two instances, Nintendo had an absolutely industry changing hardware feature (the Wiimote and true hybrid console functionality) that drove hardware adoption.
If you don't have that, you're not going to sell anywhere close to the same numbers in that scenario. This is what those people never will tell you. A Wii with a GameCube controller that has some motion/tilt control wouldn't even sell 25 million units with that chipset. A Switch that isn't a true hybrid but really more of a Wii U-2 would've bombed also.
By and large Nintendo DOES need large generational leaps to differentiate their hardware, it's 100% needed if you don't have an industry changing hardware aspect, and I doubt they have it for Switch 2. The problem is you can't just pull a hardware miracle out of your ass every 5-7 years, things don't work like that. Those types of ideas come around once in a while and not in a predictable fashion.
The Switch 2 needs to be a large upgrade hardware wise over the Switch otherwise it's going to create an impression of "hey wait a minute ... this just looks like the Switch I already have" if it's some mediocre thing that's like only 2-3x the current Switch. Past that Nintendo's developers will need it, it's hard to top Tears of the Kingdom, Mario Kart 8, Xenoblade 3, etc. etc. if you only have 2-3x the horsepower to play with.
This is why when you see the Nvidia leak, their internal data shows the Tegra T239 at 6x the CUDA cores the Switch 1 has. That's easily a full generation upgrade, you factor in potential higher clock and DLSS and you are talking about a monster upgrade. There's also life cycle to take into account, now that Nintendo knows the Switch concept is a hit it only makes sense to want the best hardware you can get so that the hardware is able to have as long of a product cycle as possible without looking too dated in later years.