To declare BK has gotten harder for companies. RP has clearly stated the new pilot requirement rules and FAR 117 is a factor. But they had at least two years to prepare for it. As for ongoing labor negotiations? Isn't 8 years enough? (RLA sucks)
It's called supply and demand. When there is a glut of a product with low demands or just an over abundant supply, costs are cheaper. When the supply dries up or shrinks and the demand goes higher, (such as gas an oil) then the costs go up.
Times have changed and if regional carriers do not adjust to the change of climate, then they just won't last.