I do agree they (regionals) are currently tapping the existing pools of last resort.

But they could still create their own funded ab initio pipeline... pay for all training and create a pipeline student=>CFI=>regional=>major. Since they're paying it does NOT have to be guaranteed flow, they could have gateways along the process. They could then adjust the throughput with bonuses at the CFI/regional phases.

The problem is that they need to lead the problem... if the legacies start parking jets, then it's too late to start such a pipeline.