I don't understand where this budget stuff is coming from? Did we ever get a budget comparison between original and sequel, or was it always a low-budget effort?
Bravely Second might be a failure in Japan but it remains to be seen what it can achieve in WW sales.
My point is that it is just too soon to start calling it a successful IP. Actually, it is too soon to call it a dead IP since its fate is still uncertain. But if SE has shown anything, it is that they don't have any interest in continuing it. Otherwise I don't think they would have developed Project Setsuna, which targets the same demographic as Bravely Default.
The IP is dead because, even as per the example of Default and its successes in the west, SE doesn't care about it. Nintendo were the ones who made it a success in the west by publishing and marketing it heavily as a must have RPG for the 3DS and throw back to FF of old.
As for the budget discussions, the sequel is built on reused assets. That, a good budget, does not make.
I'm only half joking when I say that Nintendo should just take over the IP, lol.