Sales are only an indicator. But if all that matters is that those in the community you share tastes with also enjoy a great platform with the games you like, then who cares really?
But, if the business side matters, then yeah the thread becomes important.
The day the PSVita gets exclusive big 3rd party titles (a mainline Final Fantasy) or something megaton like that, then the 3DS business might give a blink. Otherwise the stage is set for the 3DS as the sales winner, if that matters to anyone.