Time. Time is formidable. We all did race against it, at some time we won, at some time we lost. We can never know the right exact timing to strike versus it but what we do know is to wait patiently until good things flow in to our side and then we attack.
Aria the Scarlet Ammo franchise did the right thing. After 4 years, a second season (spin-off from manga) came out. The fans from the first season may have been very tired waiting for it but new set of fans joined the coalition. A coalition that only has one motive, to move forward and look for another installment.
It may take another leap of faith for a third season but the progress on the original light novel is on very good status. So material is never going to be a pain, but time will be. Time will tell us when season 3 be release.