Over 50 millions it begins to be an acceptable number. We are talking of the successor of a ~80 millions sold console, under that number it can be considered a failure.

I consider Vita a success at 50 million, but even at 50 million it's only a moderate success. PSP managed a lot more, even though PSP has enjoyed most of it's success in Japan, not so much elsewhere. UMD failed, both as a game format and a video format.

At this point, I don't see Vita really picking up steam without either a significant price drop (at least 33% like 3DS) or some kind of impossible cavalcade of AAA software, or both.

Honestly I'll be impressed when one kid in the family actually shows any interest in the Vita. Not one single son, daughter, niece or nephew even talks about the Vita. Every single one of them own a DS or 3DS, but Vita is not a word in their vocabulary. All I hear is ipod, ipad, etc. (To which I respond "Kiss my a**)

Attractive software sells hardware. Vita has very little attractive software... Thus, why this thread exists and the Vita is floundering.

You hit the nail on the head with the point about Japanese third-party support.  In order for the system to be successful, it's home territory needs to show the love and be there with support.  Iwata has done a fanTAStic job of getting all the big third-party players on board to sort of force 3DS into being a dominant machine in Japan.  I don't necessarily agree that handhelds sell best in Japan.  DS sold better in North America, but we're talking a population of 350 million + versus less than 120.  Apples and oranges.

if it makes them $1 profit. because then all the employees will be paid and everything covered but the shareholders that dont do anything wont for the particular project

Then there won't be a third sony portable console, so it can't be considered a success.

good point

Wow, that's pretty harsh, both for the Vita and the Wii U.

Actually, I'd have to disagree somewhat.  The 3DS doesn't have a stranglehold on 3rd party development in Japan because a ton of games are still being made for the PSP.  That's the Vita's biggest problem at the moment in that market.  Check out the Japanese pre-order thread, it's full of PSP titles, quite of few of which are from popular anime properties.