Admittedly, I don't know enough specifics to engage in a very meaningful debate about the issue, so take what I'm saying for what it's worth - - practically nothing.
If the threat is to lose 500 Captains in October, I don't think delaying their departure by 120 days will allow enough time to train 500 Captains and 500 F/O's, anyway. Whether it be Upgrade, Initial, Transition, whether it be currently employed or recalled from furlough, if the problem's THAT big, it's gonna take longer to fix.
Nobody is safe until they take the lump sum and depart the fix. You're not safe, the furloughee is not safe, the Captain a year from retirement is not safe. Why should you expend any negotiating capital to ensure the "safety" of this small minority group? If the Captain wants to jump ship and take his small (by comparison) lump sum, so be it. If he's as loyal to the Company as you're presenting to be, he'll hang around for a while, take a risk, and perhaps receive a bigger reward from the robust company that you want to emerge from this debacle. Nothing ventured, nothing gained, right? What this scheme amounts to, in my opinion, is an opportunity for that Captain to eat his cake and have it, too.
Park wide bodies? What about the MD-11's that are parked? (Hmmm, wait, we may have bought them.

) Again, it seems like the delayed retirement scheme is a way to cover for management's incompetence, and drive a wedge between the pilots to boot.
Buy sim time? Chump change compared to the stakes involved. Training pipeline's full? Explain that to the folks who lost their jobs as instructors. If the pipeline's full, what good does a "huge bid" do? If they can't train more, they can't train more, right? It just seems incongruous to me.
I'm sure there must be a way to make this work in your favor - - the Company wants something, you get to decide the price they should pay. Perhaps you could include language that will require the recall AND start of training for TWO furloughees for every Captain that is allowed to retire and continue flying. Perhaps you could limit the monthly cap for the retirees flying - - say to 60% of what your cap is, so they won't be replacing a "whole" line pilot, but only a fraction of one.
I don't see anybody being "forced" to do anything, except the pilots who were FORCED to be furloughed. The elder pilots have a decision to make, and I realize it's a tough one - - extraordinarily tough, at that. But it IS a decision. I don't see the fairness of sacrificing the junior guys' chances for recall and upgrade just so you can make the most senior guys' decision to bail that much easier.