I think you'll find downtraining is in fact a demotion to a smaller aircraft type, and a reduction in pay commensurate with that ie the most junior 747 Captains get offered their choice of fleet and take eg a 777 command. That means the 777 fleet may be overcrewed so the most junior 777 Captain moves back to whatever he chooses, be it 767, A320 or whatever. This is allowed for in the contract (haven't got mine in front of me but I'm pretty sure that's the case...someone can (will) correct me if I'm wrong. The company need to provide 3 months notice, or pay the old (higher rate) for 3 months.
There are options that prevent this like LWOP, early retirement etc. Trouble is the "old guys" are reluctant to retire at the moment as their super fund has done so poorly in the last year because of the financial crisis.
A compulsory retirement at 65 might solve the problem, but that's against human rights legislation.
As for the Ansett thing...build a bridge guys. It's not the current management or pilot's fault.