Then you might be out of touch because I think the average kid would think a cart based home console was "backwards" or "inferior" and stick to playing Xbox or Playstation. I mean, the Wii U install base is generally older because children and casuals don't buy their hardware like they used to. Heck, everyone I know in real life with a Wii U has been 21 or older while I know of multiple teens and pre-teens that game on 360, XBO, or PS4. People would care, this reminds me of similar arguments people made about the Wii U tablet looking cheap. "Nobody will care, Nintendo will convince them it's cool" but look how that turned out. Not a 1:1 comparison, I know, but I think you get what I'm saying.
This is all probably not worth arguing though because carts are more expensive than discs and hold less data, there's no way they would be used in a Wii U successor. 3DS TV? Sure, but not the next generation of Nintendo hardware.