fellow 3ds-er here, and yeah I'm pretty sad it's run it's course. I have an original, and a New XL and i will say, IMO, the 3ds has the best Nintendo library ever. (so far.)
And you're right about the 3d features. I remember totally freaking out at how cool the AR cards and games were and then poof, nothing else really came of it.
Luigi's Mansion, Yokai Watches, FANTASY LIFE, Animal Crossing, The Zelda's, the Mario's, Bravely Default, the list goes on. Good times for sure!
Im guessing the Switch is the new handheld, but i wouldn't stress it. Im sure in a few years they will have something awesome up their sleeve.