It's not like Nintendo needs Sony IP ... it's gravy. If Sony can sell a few million more of some of these games it's up to them if the cost/benefit outweighs the value to the Playstation console brand. Their new president did say he wants more multiplatform content to maximize profit margins, that's a fact.

There's likely a good number of big ticket IP Nintendo will be getting (back?) this gen regardless, Call of Duty is already one, Street Fighter is probable, Final Fantasy and Kingdom Hearts have a high possibility of happening given recent sales fall out and new strategy from Square-Enix. Madden NFL was always probably gonna happen with a Switch upgrade. With Microsoft's hardware division falling apart, things like Halo and Forza could be on the docket soon enough. 

There's a lot coming already as is. 

Switch > never, It's Just too weak.

Switch 2 > don't know, but first Switch 2 needs to become a successful console. Maybe It Will have some of Playstation 4 games at full price.

IF the Switch 2 gets 12 GB Unified RAM, it will need some of that for the OS and some for the non-graphic parts of a game. Don't expect more than 8 GB usable for graphics.

Already more than 60% of the gaming PCs have 8 GB VRAM and above. Until the Switch 2 launches, this percentage will grow further.

Won't happen.
Even less as Nintendo will never alow PSN integration there.

Source for that number. The top 8 GPUs on Steam are mostly all lower end GPUs that generally ship with 6-8GB of RAM. In order it's the RTX 3060, GTX 1650, 3060 Ti, RTX 2060, 3070, GTX 1060, Laptop 3060, RTX 3050 ... that's your top 8, most of those are shipping with 6GB-8GB. 

Fact of the matter is most developers are going to be stuck supporting the XBox Series S for the rest off the generation no matter what, so 8GB of VRAM is going to have to do for the majority of games (things like GTAVI included). 

If Nintendo releases Mario and Metroid on Sony consoles, then why not?

Not going to happen, unless Sony was willing to pay out the ass and probably even share a cut of their licensing fees. The fact is Nintendo has shown they can have massive success on a platform mostly driven by their own games, Sony hasn't proven that, you take GTA, COD, Madden NFL, etc. etc. off the Playstation and the brand would quickly fall below the XBox, Kratos and all that ain't gonna hold the fort. 

There would need to be a lot of incentive towards Nintendo to get them to alter their present strategy. 

Mate. Consoles don't.. Or rather cannot use all of it's Ram as video Ram, there won't be anything left for game logic.
So your argument there is silly and redundant.

However 61.37% of PC gamers have 8GB of VRAM or more... And if you include 6GB GPU's like the Geforce 3060... It's at 75.53%.

A 6GB 3060 is going to provide better performance and image quality than the Switch 2, simply no argument you can formulate will change that intrinsic fact.

One other aspect is that the VRAM on a GPU does not replace system Ram, it's in-addition. That-is, GPU's constantly stream data from System Ram to the GPU as it's much much much faster than an SSD or HDD.

Fact is, the 3060 as you put it... Is not bleeding edge, but it will beat the Switch 2.0. And will beat a Playstation 5 and Xbox Series X and will come out significantly ahead once you start using DLSS/Frame Gen. That is the sad reality of it.

...And the irony is, the 3060 released 3 years ago and will still be better than the unreleased next-gen Switch.

I don't think it's all about games it's about games, advertisement and brand power. Nintendo games could not save N64, GC and wiiu, yet there handhelds never fail. Playstation has brand power in the home console space their worst selling console is 90 million and even though Xbox is doing everything they can and have all the games you talk about everyone is buying Playstation 5.

For 3rd party IP like Fifa/FC, NBA2K, Fortnite, Madden NFL, Call of Duty, GTA, sure. Sony/MS' own games don't matter that much. 

GameCube and Wii U were also frankly under different Nintendo management and under very different market conditions that have changed considerably by today. 

The market is frankly simply more amenable to Nintendo today, a lot of the "I'm too cool for Nintendo" bros grew up and realized they were being stupid and have come around to buying Nintendo hardware again realizing childhood is meant to be fun and they want to have that experience for their own kids. Popular culture has mellowed out in general, no one cares what music you listen to or which clothing brands you wear, the hyper try hard-ness of the 90s/2000s has come and gone. 

A console like the GameCube today IMO would perform a lot better, 20 years ago I remember people laughed at something like Animal Crossing whereas today that's suddenly "cool" and being talked about on talk shows and Tiktoks and Youtube influencers love it.