I don't buy this narrative. There is a significant number of people who currently get much more comfortable journey with BA than they would with another airline, but who won't after April 2026. Priority check-in, fast track and lounge access make a big difference. These people are for most part willing to pay some extra to fly BA over another carrier. Once you take their benefits away, the incentive to not just book any random airline won't be there anymore, especially since BA has one of the most tragic products around (except for EU J).

Flyertalk is a bit of a bubble of course, but I think that mostly applies to intentionally chasing status and going out of your way to earn it. That's why I wouldn't expect bookings to drop significantly for April 2025 - March 2026 period. But when it comes to the value people give to the benefits they have, I think it's quite similar to the general population.