Right, that the line-up consists almost entirely of vacuumed up third party titles and Project Steam outside of the long announced Smash Bros and the expected Pokemon filler title sticks out to me as a system where they're buying time with the line-up.
Now, they could go announce a bunch of things later, but the 3DS being a focus wasn't the impression I got out of E3.
This isn't really too dissimilar to how they handled the DS, though. Aside from Pokemon titles, the latter half of the system's lifespan had a much smaller first party output (with a few games here and there like Mario and Luigi, Golden Sun, Spirit Tracks, etc, and some smaller titles), but it was supported more by third party support.
Whether the 3DS can manage the same thing remains to be seen, but that's probably what Nintendo's plan is at this point, to focus most of their first party studios on the Wii U (aside from teams that mostly/exclusive work on handhelds), and probably have a smaller splattering of first party stuff (possibly another Fire Emblem game, potentially a Metroid title, and some new stuff like STEAM), but bank on bigger third party support. The big launch of Persona Q in Japan indicates that there's still a big market there for third party titles, Yokai Watch has just become the next big thing, and Bravely Default has done quite well both in Japan and in the west, so it should have some life left in that regard, although it's never going to reach the mammoth status the original DS had.
They're probably buying time to a certain extent, but they got about three full years from the original DS with a release schedule around this size, so I would assume they're hoping to get at least another couple of years from the 3DS with smaller first party support (and start working on having some bigger launch titles available for their successor).