This thread is about pensions, it's also about diminishing conditions in the industry. If BA wants to change to a defined contribution scheme then BALPA must be very diligent in ensuring the contribution level is high enough. If it isn't members will find themselves seeking employment after retirement, not because they want to but because they have to.
If what is assumed here is true, that it's a done deal then the only avenue you will have to ensure adequate retirement money is to fight hard for a decent employer contribution level. If it isn't high enough you will find that more of your current disposable income will be needed to save for retirement instead of using it for frivolous things like food and shelter now.
Watch this one carefully folks or it will bite you in the arse.