Nintendo's not reinventing the wheel here. Switch is a fairly straight forward product.
If they can hold the 3DS audience, that would be a success on that basis alone IMO. To go beyond that, likely you're going to need a new breakout IP that drives hardware sales to an extreme level (like a Pokemon, Super Mario, Halo, etc.). Maybe Splatoon can blow up in Japan, but this aspect is always based some what on luck.
That said, I think they should look at allowing Android apps. I don't know if that's possible, maybe it could be done through emulation, and through their own store front (so they control the licensing fees). Nikkei did report that NX would support Android, even though Nintendo denied this, Nintendo has denied multiple stories from Nikkei (we're not making a 3DS XL, we're not developing smartphone games, we're not stopping Wii U production this year) and they've all come out to be mostly true.
So I would wait to see on that. Maybe Switch does not run Android OS per se, but has a way of emulating/running Android apps, which Nintendo would control and be able to filter out (so there's not too many apps).
