Most contracts have a phrase like this:
A pilot will be eligible for recall for ten years from his date of furlough. The employment of a pilot who does not return from furlough within 10 years from his date of furlough will be terminated.
It is my guess that not many airlines have a 10 year plan right now. Under such circumstances, and understanding that 200-400 Captains retire every year, it would be difficult to say for certain that these furloughs would not be needed 10 years from now.