Sony is playing a delicate game of still supporting its highly profitable and well selling PSP business in Japan while trying to usher in Vita. PSP is still getting tons of commercials on TV and attention in magazines. I doubt it was ever the intention to thwack 3DS, that's PSP's job and it's pretty much winning as far as I can tell (From high tie-ratio, publisher friendly perspective...whereas 3DS is very much 1st party software driven)
The only thing profitable about Vita is probably the memory card...the release calendar for PSP in 2012 is still utter bananas, probably larger than 3DS and Vita combined??? There is only 1 Wii game on the horizon and less 3DS than Vita/PSP combined, Vita almost feels like PSP HD when you use it because you go into the PSN shop and see tons of new PSP releases and basically familiar to any PSP user.
So from Japan perspective, I think Vita is in very nice position, making early adopters happy and those who aren't early adopters seem to be content with playing PSP for some longer. All Sony has to do is drop Monster Hunter 4 on Vita and they will basically have Japan tied up. The rest of the world is completely different story, unfortunately for Sony much tougher battles to be fought and new mobile technologies will be appearing sooner or later (iPad 3, Google super tablet, Windows 8 tablets)