So, I was pondering whether a 3ds VC would hypothetically be possible on the Switch.
The first consideration: The technicalities. The Switch and the 3ds share a processor architecture- ARM- which means emulation isn't actually required- just virtualization. However, the difference in graphics card architecture might make it trickier- but the Switch's will have such a large performance advantage that I would expect emulation to be doable.
In other words, the Switch should absolutely be able to emulate/virtualize a 3ds with a little work from Nintendo. Maybe a fair amount of work; like the vWii on the Wii U. But it's definitely doable.
But, what about actually playing the games?
The Switch's screen is 1280×720. The 2ds's screens are 400 x 240 on top, and 320 x 240 on bottom. (You may see "800 x 240" cited, but this is not the actual screen resolution- the 3ds has two 400-wide screens overlapping to make a 3d screen.)
If you take both 240-pixel tall screens, lay them above and below each other, and scale up by 1.5, you get exactly 720 pixels in height.
Add in some anti-aliasing, and the games won't look half bad.
I don't have access to Photoshop where I am right now, but I did a quick mockup in Photoshop. This image is 720p and the screens are full-resolution 3ds screens scaled up by exactly 1.5. (Sorry, I failed to properly center and am too lazy to go back and fix it.)
The black is the full size of the Switch screen. So you'll have a lot of black, but the full resolution images will fit and even can be scaled up by 1.5 to make up for the high PPI. If antialiased, the games would actually not look bad.
Hypothetically, you could also do something like: Scale the top screen up by 2x while leaving the bottom screen at 1x, and have a touch button in the corner to switch modes. So on a game like Smash or Mario Kart, you'd blow up the top screen to 2x, and on a game like Phoenix Wright, you'd keep them both at 1.5x.
Scaling up the top screen but not bottom would use more of the screen, of course.
So, yes- 3ds VC should be doable and actually work well.
Discussion started at here by NPPraxis