While it doesn't seem like a bad idea at first thought, I like the idea of backwards compatibility... and it has precedence in that the Genesis had backwards compatibility with a hardware add-on... I don't think it makes much business sense when we live in an age of endless ports to current systems. Also, the game pad... how is the Switch going to emulate that? You'd be tethered to a disc drive. It makes more sense to just buy a Wii U for dirt cheap when they are on clearance. Furthermore, is the Switch even powerful enough or capable of emulating the Wii U? I doubt it. Just because it can handle ports easily doesn't translate into easy emulation at full speed.
From a business standpoint, it makes sense to have customers feel invested.
But that only works well with an iterative platform - If Nintendo is ending interface changes with the Switch, then it will be alright. What that means is that all hardware going forward will be compatible with the Switch interface (motion controls, HD rumble, diamond face buttons, analog stick, etc...); future iterations can add more options, but they can't take anything away. Nintendo should hold game card media as well - all future iterations should be able to use all old cards (like 3DS to DS).
Also, new hardware will have to be capable of running all past Switch software, regardless of how much more powerful it gets: think iPhone X and iPhone 1 - while iPhone X can run virtually every phone-supported iOS application, iPhone 1 can't run most apps released in the past 5 years - Switch should be somewhat like that, except instead of annual releases bi/tri-annual releases of new hardware; also more significant than DS updates. I know Microsoft has dabbled in having tiered asset sets released with games, I think this is one of the best ideas so far for a console; PC has allowed this for decades. E.G. if Switch 2 is running a more advanced game that supports older hardware, it might go at 60GFPS and 1080p (or higher) instead of 30 FPS and 900p and support faster load times.