At this point I don't understand the whole discussion about Vita in Japan anymore, what are you guys discussing exactly?
There is a demand for the console, there is going to be a market for it and studios are going to keep releasing games based on their perception of that market. The same reason that 3DS gets Hatsune Miku Mirai and Vita gets Hatsune Miku DIVA.
If you believe Vita is going to vanish and 3DS is going to get the whole handheld market at this point, well, I'm pretty sure that won't happen.
2012 software 3DS/PSV=90%
2013 software 3DS/PSV>90%
That looks like 3DS having the whole handheld market to me.