Well, this is rather obvious, is it not? Bravely is a very young and fresh series that's just getting started. If people have lost interest in it by the time the second game arrives, it's safe to assume that it doesn't make sense to explore the series any further. The second game always is the one that decides whether or not a first game was a fluke or if there's actual interest in a game as a series.
Sales of the first one very definitely encouraging, however. If Second reaches yet again 300k people, I think we don't have to worry about the series fate...
I wouldn't mind seeing Bravely on other platforms too, btw. While playing Bravely Default I some times stopped and wondered how amazing the backgrounds could look on a platform with a higher resolution. When zoomed out a lot of details are getting lost on the 3DS, sadly, and when zoomed in a few areas in the game are a tad too blurry. Nothing bad (and I absolutely prefer it to be 3DS exclusive when that means that Nintendo will keep publishing it in the West), though, it's still a beautiful game on the 3DS too.
I do wonder if they are going to change something with the backgrounds in Bravely Second, though. I think it's obvious that Bravely Default was made without the 3DS XL in mind; the graphical flaws are more apparent on the huge screens.
Was Bravely Second announced for NA?
No. But that's to be expected, considering that Bravely Default is not even out in NA (and just got released a few weeks back in Europe). We'll likely have to play the usual "wait and see" game until after the game releases in Japan.
When is Bravely Second supposed to be released anyway? Next Fall?