The "kids growing up with smart devices" is the thing that I think bothers Nintendo the most.
I think they'd be OK with those devices taking away casual adult players, but the entry level kids market is a real kick in the junk to them.
Every time I'm in an airport these days (and I've been in like 8 the past year), the number of kids I see using their parents or their own iPad/smartphone to play games on outnumbers the kids with DS/PSPs by 4 to 1 at least everywhere.
2DS is obviously I think trying to take some of that audience back.