Oh, come on. The question wasn't whether or not Nintendo has stopped making games, it was whether or not they've stopped making games for DS. And the answer is obviously no, because they just released Zelda last week. But it does seem like they've been slowing down. Of course they'll stop making games for DS someday, and I don't think anyone can deny that the DS is getting, shall we say, "long in the tooth". It makes perfect sense for them to release a new iteration of their existing handheld to buoy up sales of their aging platform while they prepare for the next big thing.
They wouldn't bring out a big game like Spirit Tracks and a new version of their handheld if they were going to dump the system for something else next month, but the fact remains that they will dump it eventually. That's just business. That day it getting closer and closer all the time. I would be surprised if they were not working on games for their next handheld right now.