I hope that it will do 7 million lifetime in Japan, and you? 

It depends on when it will be discontinued!I will decide and I will answer to your question soon!

It's difficult to know. Japan is the only place in the world where the Vita is almost competitive (also the only place period where Vita numbers are greater than PS4 ones). It has sold aroundd 3.5 million already, and I think it will sell 2.5 million more there.

I'll go with 5 million.

The question is how long the Vita will be popular in Japan.

PS machines always have legs, the PSP is still getting new games. The Vita sales will continue until the 3rd party support abandons the ship or producing the console isnt profitable due to poor sales. The release of the next Nintendo handheld will be the event that kills the Vita (in hardware sales). When will that be, I hope 2017-2018.

6.5 millions

It'll get to 6 Millions easily I think. No doubt about that. It's been selling steadily a million per year now, and if we give it two or three more years, it can get there. But I hope it'll do more.

Over 4 million definetly 4m-4.5m, 5m at the very best.

This is probably the last year of Vita relevance in Japan anyway.

It's been a long time PSP didn't get any games that boost it's sales,Vita won't survive with late port and niche games