There’s no such thing as a 100% route tbh. BA have never officially committed to a route to have the seat. They’ve only internally announced that they aim to have JFK as fully CS but even that is subjected to the occasional aircraft swap. Until 2024 it’ll still be quite hit and miss as to whether a route will be CS or not. However with the resumption of 787-10 deliveries, the nearing conclusion of 777 refurbs (which seem to be running slower than expected, seems really unlike that BA will hit the target of refurbishing them all by end of 2022 as they announced, though not impossible), conclusion of A350 deliveries, it should be a lot better by summer 2023. However there are still the 787-8s and 9s as well as A380s which form reasonable a chunk of the fleet too.