Lol indeed.
But on topic, I'd like to clarify where my POV is coming from. I'm glad you broke down how much the devices technically do have in common, but where I worry is the practicality in this shared library approach, if it means the games are going to be exactly the same minus resolution differences. If Nintendo's motto is "the hardware drives the software", then why make two or more pieces of hardware that are virtually the same, and yet expect and have players expect unique software for each version of that hardware?
That was the appealing part about pairings like the SNES/GB, GBA/GC, and DS/Wii; yeah they had the expected similarities but enough differences, technical and otherwise, to drive the need for unique games for those platforms specifically tailored to them. That's probably the biggest reason why Nintendo's been able to justify supporting two platforms per gen. Now, I'm aware how other factors made it easier back then vs. now; game tech was more exotic, and costs were cheaper. There was also less competition from other markets, i.e smartphones and tablets didn't exist. And Nintendo as a whole was in a stronger position in those days, especially w/ DS and Wii.
But I consider those incidental factors, b/c there are still many factors that were deliberately formed as a result of those hardware differences, such as not being able to share engines and assets, that resulted in the unique 1st/2nd party software libraries between their consoles and handhelds of the past few gens. It may've made for difficulties at times (software drought, costs eventually I'm sure), but it also made sure each device had its own unique library worth getting them for.
This is interesting, b/c if people say exclusives don't sell Sony or Microsoft systems, the exact opposite is true of Nintendo devices. They mostly sell on their exclusives. People don't tend to give a shit about 3rd parties on Nintendo and haven't seem to since the Gamecube era, and arguably going back to N64 in some ways as well. So if people just come to accept that Nintendo's own games for the NX family are going to be the exact same across all devices, minus some token features thrown in that may make gimmicky use of one or two features exclusive to that device (and the aforementioned resolution), that's going to give a lot of people less reason to bother getting both or all of the devices, especially if 3rd party support ends up being questionable.
Which is why I honestly think Nintendo means w/ the whole "shared architecture" stuff, is that the devices may share some common engineering features and provide similar programming environments, but the "shared" things will come down to stuff like sound files, graphic files, base code, engine assets etc. I don't think (or feel it'd be a good idea) we'll see Mario Galaxy 3 on both NX console and NX handheld; if it comes down to that, there's no reason to force people to buy it twice. Just let them plug the card-cart or what-have-you into the console and handheld, since aside from resolution it'd be more or less the exact same game, right?
Shared game library. Sounds like a decent idea on paper but it lowers need for getting each particular device in the family in the long run. Hopefully Nintendo can find a balance there. I know why the idea sounds good, but it doesn't lend itself well in being practical, knowing what role exclusive software can have for spurring sales, especially true for Nintendo. It's something to especially consider in the West, where handhelds struggle against smartphones and tablets.
If the library ends up exactly the same between devices it gives their handhelds less appeal to Westerners and out of the two lines their handhelds are the ones that have consistently done well even in face of smartphones and tablets. I don't think Nintendo can afford to let that happen. These things need their own exclusives that justify the unique features of their given device form factor, or there's almost zero reason to get them when you can get the superior device in the family.