Yep, I'm hoping this is the case. If you had a 3DS and a Wii U you'd have quite a bit to play on each, but if you only had one you'd be missing out on a lot.
All that's left is to space out the software accordingly. It's alright to skip January because that's a horrible month to release games in, but they can't leave summer completely empty while having 50%+ of their software out from september to november.
They also need to work with 3rd parties to make sure they don't clash.
And the cool thing is, the shared library would keep costs down but increase profits. There doesn't have to be a Bayonetta situation where because the install base is lacking the game has to die. If one it outperforming the other it's still good because it's still more software to sell.
If Nintendo plays their cards right, they can expand their market share and increase their revenue drastically in the next few years.
The only downside would be the games wouldn't be as impressive as we'd like, but if you put a big enough budget behind a game on a platform like that it can look pretty nice
(like Killzone on Vita)
And if you develop the game with the console in mind you can probably make some very pretty games on both systems especially if it's stylized (like Wind Waker, a GCN game which still looks great to this day with a simple up rez). Hoping it leads to 1080p 60fps console games as well
By just releasing one Mario Kart for both devices, or one smash bros, or Zelda... they can save resources to work on more IP, new or old. The userbase per game will be larger (across both platforms) and you will create a more dynamic online community.
They can still make impressive games, that look a bit less impressive on the handheld. Or portable games, that can be fun for a quick session on the home console.