Nintendo has released its latest batch of sales estimates for the upcoming fiscal year, and while the company plans/hopes to sell a bunch of Wii U consoles, 3DS units, and even a few classic Wii systems, it estimates that it will sell zero units of the family of Nintendo DS systems which signals the impending retirement of the hardware; of course, the original DS and DS Lite are long gone, but the DSi and DSi XL are still hanging around.  You can buy a DSi, but don't count on them being around as new items for much longer.  GoNintendo summarizes:

Looks like Nintendo is finally going to move away from creating the Nintendo DS.  The current fiscal year, which ends March 2014, forecasts total sales of the Nintendo DS at 0.  Nintendo hasn't officially said that they're stopping production of the system, but they did offer up this statement.  What they say makes it clear that the DS is winding down.

Nintendo will continue to sell Nintendo DS Hardware but is not revealing a unit sales forecast at this time.

With that said, the Nintendo DS family of portables managed to ship 153.87 million units around the world.

All hardware is retired eventually.  I remember the mourning period when the Game Boy Advance packed up and left town; the last games out the door were all kiddie licensed games produced on the cheap.  The Nintendo DS has enjoyed a more honorable cool down period as the best games for it continue to be sold.  New Super Mario Bros. and Mario Kart DS are still out there on store shelves.  You can still find copies of Super Mario 64 DS which released nine years ago.  I carried my DS everywhere for several years, taking it to college classes, multiple E3s, and basically everywhere I thought I'd have a chance to get in some quick Mario time.  I'm sad to see the DS go, but it had an amazing life and brought us some fantastic games.  In addition to the titles I've already mentioned, I also highly recommend that you track down Mario & Luigi: Bowser's Inside Story, Tetris DS, Kirby: Canvas Curse, Metroid Prime Pinball (with Rumble Pak if your DS features a Game Boy Advance cartridge slot), Yoshi's Island DS, Kirby Super Star Ultra, the three Castlevania games, Chrono Trigger, and Kirby Mass Attack.  The DS library will live on thanks to the Nintendo 3DS's backward compatibility features, but the DS hardware has earned its place in video gaming history and deserves a honored retirement.