I snipped points 3-5 because I don't think that the discussion can go any further with them.
1. Looks like you rushed the numbers. Here are the same comparisons between the third and sixth fiscal year for other home consoles.
N64 - 7.9m, 500k - ~7%
The NES doesn't have individual numbers for its first three fiscal years in Japan and the launches in America and Europe were staggered between individual states and countries, so a proper like-for-like comparison is not possible. The DS's value exceeds 100%, but that's not the norm for consoles.
What you call a huge difference between the SNES and Wii is among the closest values you get in this kind of comparison. Personally, I don't consider such a comparison valuable due to the involved variables, but going along with your suggestion reveals that your conclusion is wrong. The Wii is most similar to the SNES; other consoles show significant differences to the Wii.
Wii's third party support has first and foremost to do with the contempt that third parties held for the console. They usually didn't want to develop quality titles, but were rather looking to cash in with quickly made games. Since consumers stopped buying the low quality games while third parties didn't want to make quality games, third party support was scaled back a lot. Consumers were definitely interested in playing Wii games, because Nintendo games sold well throughout the Wii's life. But even for Nintendo support it looked lackluster from 2011 onwards, because the 3DS launched in early 2011 and demanded Nintendo's attention, even moreso when it struggled.
Overall, it's misguided to conclude that the Wii's decline is due to a reason like fad or unwillingness by consumers to buy more, because the situation of the software pipeline provides the more logical reason that the sharply declining number of interesting game releases resulted in the declining hardware and software sales.
2. Point 3 in my previous post addressed this already. You are of the opinion that consumers should buy a brand, but I explained that Wii and Wii U aren't similar consoles despite both using the same brand.
I don't think it makes sense to put much stock into the late life support of a console and how that translates consumer confidence in a new console. The Wii U's software pipeline was woeful from start to finish and awfully bad in 2016, but none of that harmed Switch. The Wii U failed because of what it was, not because consumers were supposedly very dissatisfied with the Wii.
Nintendo decided on the Switch route in late 2013/early 2014 because both the 3DS and Wii U had run into extended software droughts due to rising development times for games. Under such circumstances it would be incredibly difficult to adequately support two separate Nintendo consoles with first party software, that's why Nintendo looked into ways to solve this problem. The other big factor is of competitive nature because at that point in time it was already clear that Sony was going to exit the handheld market; that would have left Nintendo as the only console manufacturer to support two consoles if they had continued with the same strategy. It was a decision that was equally motivated by the circumstances of the home and handheld market, because Nintendo wasn't satisfied with 3DS sales either.
Wii is more similar to SNES in year 6 than N64 or GC. Ok, but Wii still didn't last as much as SNES or NES. That was always my point. You will always said it droped so much because if was intentional because reasons you say and i will always say it happened because Wii in 2011 was not a compelling console anymore. Zelda Skyward Sword, one of the most hyped games ever launched at the end of 2011 with critical aclaim and despite the huge install base of the Wii it was incapable of being a comercial success like Twilight Pricess. Why?? Was because the game in itself was bad??, or was because people didn't liked to use nunchuks anymore??, or because the game looked aged in 2011??, What was the reason?.
And a fad, to me....because i don't know how to express myself any better, it's something that is VEEEEEERY HUGE (way more popular item against direct competion or something so new that creates a new market in itself), and then in a year or two, even 3 if you want....a variable period of time, then...poof is not the most popular anymore. Examples: Singstar, EyeToy, Kinect (KING OF FADS), Guitar Hero, Just Dance...3D gaming hype didn't even last the launch of the hardware..... Wii Nunchuks style of gaming was IN MY OPINION, in the same category of those fads. That doesn't mean that Wii didn't had a big library and some very good games, but the reason why Wii sold muuuuuuch more than N64 and GC was not because it had 3x bigger or better library of games. That was always my point, and you can take it or not. The fact that Nintendo decided that they could not compete with a home console only anymore with the launch of the Switch was the confirmation i needed. The market for console+handhled shrinked last gen for Nintendo, not because of Sony, not even for smartphones or tablets. It was because Nintendo could not mantain the level of success of the Wii in the home console market (hardware becoming too expensive to compete against Sony and Microsoft, lack of 3rd party support, ...whatever the reason). DS did bonkers and 3DS did really fine, so Nintendo realised there was only one solution possible to maximize success: a Hybrid console (or a superpowerful handheld depending on the person). We are in 2019, and i've made my mind about the reasons of the Wii success for a decade, so i won't change my opinion now. Anyone can have their own theory. I respect yours and i accept some things you said, but the main reasons are still intact in my mind.
I appreciate your points but i think we both agree we have to stop here. As always a pleasure to discuss things this way.
In my mind the best Nintendo home consoles based on software are in this order: SNES>N64>GC>Switch>Wii>WiiU>NES, So that's why i defended N64, I honestly think it was a better console relatively to its time if we only talk about the games.