You nailed it rickt86, you said the "current model is not sustainable". That is correct. The model is going to significantly change. Always has, always will. Ask an old mainline guy if in 1990 they saw the RJ coming. Ask a retired mainline guy about the dawn of the jet age in the late 60's. That was a real pilot shortage, and they hired people without any flying experience, oh the humanity.
I don't discount the significance of the 1500hr rule change. But, that's just it, it's a rule change. Meaning, they can make another change to accomodate some shortage. Look at how quickly the retirement age went from 60-65.