I think it's important to look at history. From statistical observation, Nintendo's home console sales have declined gradually since their debut if you ignore the outlier that was the Wii. Their handhelds have fluctuated, the GB was an astronomical hit and the GBA, given its shorter lifespan, was greatly successful too despite being perceived as a "portable SNES" and was eventually overshadowed by the DS. The DS is by far their most successful piece of hardware they've released, and honestly, there will probably never be a system they release that beats it. Not with the drastic change in market conditions since the DS released where mobile prevails over any other portable gaming device. Even the sales of the 3DS were butchered by mobile, having sold 65ish million in 6 years while the original DS did 143 million in 6 years. This is half of the original's success in the same timeframe. If Nintendo were to release another "DS" successor, the sales will probably halve again.
Nintendo focusing on one system is ideal. The Switch is already being deemed as having not enough games. The easiest way to alleviate this is by having Nintendo's EPD division working on a single system to ensure as many games are on it as possible to prevent droughts. Third parties are far too skeptic and observant to rely on to prevent droughts, so Nintendo must try their hardest, and that's with eradicating the coexistence of two devices. The 3DS is quite dated hardware-wise; Nintendo has even resorted from creating new games from their franchises to remaking old ones for the system (Metroid 2 remake, Super star saga). So, I can't see it living past 2018. Neither can I foresee a successor to it either.
The Switch hitting 30-40 million lifetime seems very, very feasible. I'm inevitably biased in acknowledging how much Pokemon will do for the Switch in success with this prediction too. Pokemon is the most derivative and formulaic IP that Nintendo has, but I guess the fans don't care. I would hope they would add some HD rumble functionality with the game (maybe with Pokeballs) and heck maybe optional motion controls, HD, a full 3D environment...I'm obviously not a fan of the franchise but this is a huge opportunity to create a groundbreaking Pokemon title that drives Switch sales. I heard somebody saying "Pokemon alone will outsell PS4" which is pretty ridiculous since the PS4 is on track to outsell 3DS. Nintendo needs to get all their popular IPs on this system. We've already got a 3D Mario, 3D Zelda, pending Pokemon, Prime 4, Splatoon 2, Fire Emblem, Yoshi and Kirby...now all we need is a Smash port, Mario Maker 2/port and the new Pikmin (4)? that should be coming. This should be enough to hit 30-40 million along with a few third party titles imo.
Sorry for the rant.







