My guess is EVERYBODY on the list will get a letter asking their intentions: accept recall, defer recall, or resign seniority. There will be some that don't receive the letter or don't respond within the required 7 days and are immediately terminated. That will give the company some idea of what they're dealing with. Then they'll send out letters to the first batch for training dates (in March if the recurrent brief was accurate).
Training spots will be the limiting factor. I just got back from recurrent and FSI is starting to lose instructors going back to flying jobs across all the learning centers. It takes the better part of a year to get an instructor fully up to speed.
Actual number of recalls? All who want to come back, eventually. Barring another economic meltdown, I'm starting to think we'll be hiring off the street by the 4th quarter of 2015.
The best part will be watching some folks come back, get a new type, get current with a couple of hundred hours, and then blow this popsicle stand for a better job. Jordy will be standing in the hall looking like the kid who just had his ice cream taken away. It will be epic...