speedbird2018 is spot on. My colleagues in both the US and the UK who fly in Y are opting for other airlines.
They fly BA from London to the continent ... but basically that's just because the fares are so cheap.
From what I see in the US, BA is marketing their economy product as the cheapest option. There always seems to be a sale, and the marketing focuses 100% on price.
Now they plan to only offer 25% miles in the FFP ... and basically they are losing the business traveller that has to fly in Y.
Even with the upgrades supposedly getting better in the new programme, a Y traveller can only upgrade to WT+, and only on the higher priced Y, B & H fares.
In J and F ... BA is great. But it is pricey.
While there is some debate as to whether or not MRTC is a success ... I think it is safe to say that WT+ has not been a success for BA. For the good of the airline, I think BA could use WT+ to cater to the business Y traveller. I'd take WT+ over MRTC any day.