I don't think they're developing for 3DS at all. They're probably going straight to NX,  and Nintendo didn't want to reveal that. 

They could shift focus to the NX at any moment, specially if they work on small games and apps instead of bigger releases. Also, I don't thinkthe 3DS it's on its last legs just yet. 2016 looks to be a bigger year than 2015, and the console could sell well enough during the NX first years if Nintendo makes a decent pricecut. In fact, I would be willing to bet than the WiiU will be replaced before the 3DS.

I could be mistaken, but I'm pretty sure it's the studio who originally made Portal.

Because Digipen is a university that's focused on game design, meaning that the studio that's developing games will most likely consist of college graduates and interns. This would also mean that the 3DS would be a better place to start off as opposed to something as complex as the Wii U.

More studios is always good news in my book. And this is a very interesting project, giving rookies the chance to work on the 3ds while helping to fill it's library. It might also make future third party devs more willing to work on nintendo systems because they've worked with them during their education.
Should bring in some fresh ideas.

Sheesh so many people quoted me and yes you are all correct! xP

A studio doesn't stop when the console does.