There are a number of sad subtle things that have been lost, and needn't have, if BASSA had negotiated properly.
1) Promotion opportunities for those on legacy fleets have been massively reduced. If you are Main Crew now, that is pretty much where you will stay. Any retirements etc will just be filled by a new joiner on MF.
2) Because of the infighting between crew over staff travel, the previously 'grey' area of upgrades was defined. The CSD has now lost the right to upgrade forever, so a big perk has gone.
3) Routes will continue to transfer to MF. Many will see their favourite destinations go, perhaps where they have family etc.
4) Legacy crews will enjoy less and less variation in the routes they fly as MF expands.
5) BA doesn't need a VCC scheme anymore, it has MF. As it grows they negate the threat of strike calls from legacy crew. If BA decide to look for more cost savings during the next downturn, any threat of a strike will mean nothing.
It's all very sad, it didn't need to be this way. And to think some are hailing it as a 'victory'...