Not only in Japan.
Even worldwide...

I think not, PS Vita will be longer supported in Japan than New 3DS.

I dont doubt Vita being supported longer, in fact i agree. but there's a chance N3DS can temporarily surpass it there........ Well maybe :0

Yeah, it's massively outselling it every week.

Also, for some reason I feel like I've seen this thread before?

I think your talking about Vita vs N3ds in 2014. I made that, i thought it be interesting. Fortunately N3DS actually to my surprise beat vita by about 100k-150k.

Of course it could supass it, it is just my opionon. I think it will be a very cool battle!

No problem, like i said i agree that vita support (well japan) will definitely be alot longer than 3ds, but thats also due to the fact Next Nintendo HH will be coming out 2016/2017!!!

Vita vs N3DS is the only good war we will get. 

I think so, there's no competition and the vita is a lost cause.

Yep, easily. Give it another year.

In 2014 PSVita have sold 1,150,000 unit, and it is dropped by 35% compared to last year for now... so, probabily that in 2015 Vita will sell 700,000-800,000
This year 3DS will probabily sell 2,500,000, with 80% of sales for the New version, so, N3DS will sell 2,000,000 this year in my opinion.
The gap will be +1.2M...

By end of 2015 will have:
Vita: 4,500,000
N3DS: 3,200,000

Yeah, in 2016+2017 N3DS will break the other 1,300,000 gap imo.