My company has just said yes to a deal whereby crew can bid for reduced lines of around half the minimum normal line. We are currently all on minimum guarranteed hours. One senior guy tried to get them onside to job share years ago but to no avail.
As everyone has said, the fixed costs of employment is the issue (about 35k Aust) for a 737 Pilot in my company. The company have allowed it for up to 2 years at a time and have obviously decided to suck up the cost of keeping people rather than train them from new when the ball rolls again.
All the benefits of job share as far as I can see.