There is no way legacy crew will end up on the new contract:
Watch this space. Redeployment clause springs to mind. Trust me BA have not spent all this money on busting BASSA for nothing.
Personally sitting at home with no work, and getting paid would be a pretty good outcome, but seriously that's not going to happen is it?
I think a lot more non contractual (or so they say) changes, are going to be imposed very soon. The job will become less palatable , new fleet will expand, old fleet will do only the non long range, MMP will stop. Eventually no more old fleet. Choice then leave or be redeployed on a new contract.