Careful, BE.
The assumptions made in said letter are based upon pensionable pay frozen at RPI and your final pension having an LPI cap of 2.5%. Remember as pay rises generally tend to be more than RPI, the gap between your final salary and your pension will progressively increase. Once you retire, your pension will not have any protection should inflation be greater than 2.5%, which if history is anything to go by, it will be. If BA go for BALPA's 5% LPI and RPI+ pensionable pay rises, which BA can afford with the money that is now on the table, along with a review process and a decent percentage for BARP, a deal could be done.
Having said that, I agree entirely with the second part of your post.
HF