Nintendo has historically been good with sticking with successful brand names like the Game Boy and DS, both lasting more than a decade with the GBA and 3DS lines. I'm doubtful they will scrap the Switch name as it's a more universal and appealing term that has become its own brand.
Was there a significant generational confusion during the 3DS launch? I have vague memories of it, but it seemed fairly clear that it was a more powerful DS followup capable of more advanced 3D.
Looking back, it's honestly impressive how well Nintendo was able to maintain design continuity with its handheld systems, both within and across the GameBoy and DS brands, and even more impressive that they followed up over a decade of that by bungling the Wii U.
When you open the 3DS box, you see a plastic rectangle of similar size to DS line. You open the clamshell and everything from the DS is there: two screens, stylus for the bottom screen, dpad, all the buttons, card slot. If you owned a DSi, your AC adapters will still work here, you'll recognize the system menu's layout and navigation, and any DSiWare can be transferred so it shows up on the 3DS menu. Pop a DS card into the slot and it'll come up on the menu, same as with any of the new 3DS games. The most significant change is that the dpad has been shifted downward in favor of the circle pad, but the circle pad will do everything the dpad did – you can even use it to control DS games. The 3D screen, gyro control, and AR camera are all additive features to the existing DS featureset, and if you had to trade in your old DS or give it to your little brother in order to buy the 3DS, you can rest assured that your DS backlog is still waiting for you.
Now the console team has decided they want to do a similar style of follow-up to their own seventh-gen device, so what's the Wii U gonna do? For starters, its flagship controller is no longer the Wii Remote, but the big honkin Wii U GamePad. This thing looks more like a 3DS bloated into a controller than it does like anything on the Wii, but it won't actually play games on the go. To set this up, you've got to make room for this thing's charging cradle, plus the system itself. No more cool vertical stand, this console is rounded so it can't be mounted vertically without assistance. You boot it up and the TV shows, uhhh, something? Where's all the games and stuff? They're on the GamePad, in a menu that looks like the 3DS system menu and controls in the same way. Huh. Okay, if I put in a Wii disc, it... shows an icon for the Wii menu? It boots into the Wii instead of playing it directly? Why not just play this on a Wii and skip opening the Wii U menu if it doesn't support the new controller? I can display the game on the controller, but my sensor bar's still by the TV, and the controller buttons won't work.