It should be quite clear to all what to do. Age 65 is coming, DEFO is happening, bases are disappearing etc.
Compensation for this is written in your contract if you joined before COS8. It's very simple. There is no need for bickering just as there is no need for negotiation on this. Full bypass as per contract must be paid to all affected.
I joined in my third decade, had plenty of jet time but still came as SO. I don't mind sitting here as FO till well into my fourth decade - but I must be compensated. NOBODY told me at my interviews that my projected career earnings will be substantially less due to above mentioned developments. If CX was honest about this I most likely would not have accepted the offer - simple career earnings math.
End of story.