M.I.S. said:
If you're going to make assertions such as this, you need to provide a link. Why would any CEO state that a product their company sells doesn't provide much profit?
You have no knowledge whatsoever (nor do I) of how long the 3DS will remain on the market. GBA only had a shelf life of 4 years before being replaced by the DS (and was quickly EOL'd rapidly) despite selling 80 million in those 4 years. And the market is much more volatile now than it was then.
The GBA wasn't killed off quickly after the DS came out just 3 1/2 years after its release, though. Quite the opposite, the GBA had a bit over two full years of first party support before finally being killed off, and third party support continued for another year past that. It ended up with a solid 5 1/2 years of good support, with one year of fading support afterwards.
It's the Game Boy Color, replaced after just 2 1/2 years, which really suffered the most as far as lifespan is concerned. Unlike the GBA, for the most part GBC first party support did not continue after the GBA"s release (Pokemon Crystal was released in the West shortly after the GBA, but not in Japan; the only other US GBC release after that, I believe, was the late 2002 Hamtaro: Ham-Hams Unite, which was released before the GBA in Japan.), and third party support faded to a trickle after the end of 2001, until finally the last releases came out in late 2002-early 2003 depending on region.
The DSi compares well with the GBC in this regard, given that it's only a couple of years old but is pretty much dead now. The DSi was not marketed as much as a followup as the GBC was (almost no card games require it, most notably), but still, it is a different system from the DS, and it is clearly going to have a short lifespan. I highly doubt that the 3DS will be similar, though, and these good sales make that chance more and more remote all the time.
I mean, you're right that we don't know, but it seems quite unlikely that the 3DS wouldn't last a full generation.