I disagree that it will replace both. The DS brings ruggedness and a smaller form factor. I can't see me bringing this little flimsy tablet with probably max ~8 hours of battery life with me on one of my travels. My 3DS has had no trouble being thrown into a ruck and dragged across SE Asia needing a charge a week.
Maybe I didn't convey it clearly, but this is what I was trying to get at by different packages and price points. Consider how the 3DS is marketed. I can buy the cheap 2DS, the middle of the road 3DS, or the high end 3DS XL (might even be missing some options).
At the end of the day they all play the same games. I bought the 2DS for my 3 kids because it is cheap, but also because it is the most rugged with it's non folding uni-body so they are less likely to break it.
I bought the 3DS XL for myself because I have poor eyesight and need the bigger screen and I'm less likely to break it.
If Nintendo does something along these lines I suspect people would buy multiple Switches per household. Based on their history it's not unreasonable to suspect that something like this is in the works. I doubt it would happen at launch since, but over time I will not be at all surprised to see different versions of this system offered.
This is my guess. Since it uses cartridges and a single screen, there's nothing stopping them from selling a version which is a single smaller unit with better battery life but without TV/local multiplayer capabilities.
