Maybe the NX hybrid is expensive and Nintendo needs to have a cheaper handheld option until it can get cheaper. A year or so.

... or these games were still in the pipeline and not really needed for the NX.

We'll see then they launch the NX.

I love my 3Ds ever since I bought it. Never understood why people called it a failure. It has a fantastic game library and fantastic support from nintendo. The kind of games and support the WiiU needed. Im gonna be looking forward for Monster Hunter Stories and the DQ games.

Here is the American Gameboy Advance lineup of Nintendo published titles the year after DS released.

The Legend of Zelda: The Minish Cap, Mario Party Advance, Pokemon Emerald, Fire Emblem: The Sacred Stones, WarioWare: Twisted!, Yoshi's Topsy-Turvy, DK: King of Swing, Donkey Kong Country 3, Dr. Mario & Puzzle League, Mario Tennis: Power Tour, Final Fantasy IV Advance

3DS having solid support in 2017 means nothing for NX.

Back when the DS launched, the GBA kept receiving content for awhile too. I think this is the same sort of thing.

I'm still in the camp that the NX is a platform rather than a singular device and they're still developing significant 3DS games going into next year because they're not going to release the handheld form factor until the holiday season.

Looking at the 2017 games announced, none of them are being developed by Nintendo's major internal teams or larger subsidiaries like Monolith, Retro, HAL, Intelligent Systems.

Poochy & Yoshi's Woolly World is developed by Good-Feel.

Pikmin 3DS is rumored to be developed by Arzest.

Mario Sports Superstars is being developed by Camelot Software.

Ever Oasis is being developed by Grezzo.

Dragon Quest 8 is a localization of a 2015 game developed by Square-Enix.

It doesn't mean nothing guys... Even PS2 got some of the it's best games after ps3 launched, the same for PS1 to ps2 transition, GBA>DS, DS>3DS, 360>XONE, PS3>PS4, heck, even NES got some big games like DR. Mario when SNES were already two years old. For a successful system it makes all the sense to keep supporting it because there's already a big install base that still can push software to some solid numbers, and development takes time and it isn't so easy to stop what is being done right now to adapt it for a new system and generating costs for a system wich is still a bet. It's easier to happen like happened a lot this gen, but always happened before, releasing a game in one gen and than just make a upgraded version for newer systems.
It's different when it comes to Wii U because it's pretty much a dead system, sure, some games will get cross gen release like Zelda, in the fashion of what happened with Twilight Princess, but i do believe it is just because Nintendo want to keep their promise to the fans of releasing the game on Wii U since the developers are pretty nuch sure focused on the nx version, just like happened with Twilight Princess.

Back then it was way easier to develop games.

downgraded ports and low budget spinoffs dont really take a whole lot of time either

But they still take time and resources. You can say not enough to hurt the NX, but only time will tell. This does mean what I said though, no unified library, which for me was the single most important thing.