The question seems to be, is it their fault or BA's that they are 'stuck in a corner' with no-where to go?
Should they have had they're eyes open and jumped ship while the going was good, (i.e. pre paris crash, 9/11 etc) retrained, grabbed those transferable skills in whatever, taken the short term hit in terms of pay and conditions for the long term prospect on continued employment, albeit in another job, industry, etc?
No of course not, because they couldn't predict the future, just like everyone else. To my knowledge, BA always made very public statements in the 1990's to keep Concorde flying until 2010 etc, so it would have been a fair and reasonable assumption that there was some long term continuality.