The BA DEP pension scheme will not change for a very long time. Any extra cost incurred by improving the company pension contribution would come from the same pot that will be used for future terms and conditions negotiations.
Those DEPs starting on the 'B' scale will be in the minority for a very long time and no final salary pilots are going to rock the boat and accept reduced benefits just so the new boys (and girls) can get an extra percent into their pension fund!
If you want/need a good pension BA may not be the place to go.