Exeng I have had a small internal airline an international carrier and an exec flight department go t*ts up while I was working for them and there was no option but to toddle off quietly. I suspect that the majority of flight crews have had similar experiences. I found that out about aviation as I went along and I would be very surprised if the F/E's on Concorde didn't consider it a disdinct possibility. No, I do not know what was promised, nor what was stipulated in their contract, but I would wager that they have been offered their full contractual entitlement, that they have probably had long and fruitful carreers, and have earned every penny of their salary. I suggest that they were paid what they were worth, and now sadly, their jobs have come to an end.
I have never believed that simply because someone was paid more than me they were overpaid, and 'fair' is a very overused concept.