Seriously? If someone's a 73 Captain at lCal, they're only a few hundred numbers from being a 756 Captain, and could reasonably expect to hold 756 Captain within 2 years. So your question should be:

"The career expectations (career earnings) of a currently unemployed pilot who will return as a junior FO for awhile and eventually become a wide body captain for one year starting at 64, vs a 35 year old lCal pilot who is currently a narrow body captain and will become a 756 Captain by 40 will be massively different."