Cornflake
Your point 4 cannot be correct, as there IS no risk to being part of the "so-called future" (of BACX?) for secondees. I think that is PRECISELY the point of your colleague's term 'golden parachute', isn't it? (in any case 6 captains out of 60 pilots, isn't exactly a stampede, and at least 2 are going to longhaul commands!)
Your point 3 is also highly debatable, as British Airways ALONE decide whom they 'invite' for interview; eg. 777, 747, or A320 type ratings. Since none of these types are currently on the BACX AOC, how can ANYONE currently create a 'meaningful transition from BACX to BA'? (And what about the reciprocal?)
The job market is just begining to open up, thanks in no small part to the predictable, cyclical nature of the industry. People WILL move up the 'perceived' career ladder, which will involve changing employer from time to time.
The good news is likely to be that most employers will have to try a little harder to retain those pilots that are seen as difficult to replace.
Enjoy.