I follow the logic, but would be curious to see the actual numbers. I would suspect it's closer to 1:10 who will be engaged v. disengaged, and the incremental losses from disengaged current golds and GGLs could be much greater given the gulf between silver and gold.

I don't game the system and do tier points runs, etc. I have participated in the BA Holidays double tier points offer, the credit card offer, and sometimes I will take an extra connection if it doesn't add more than two hours to a long-haul. Depending on the year, I spend £12k-£15k (2/3 employer). In my case, there will be an immediate £2500 loss from downgrading from Club Europe flights (to my second home) that I booked only to keep status. As soon as I'm confident I'll hit the £7k for silver, which could be credit card spend + one work trans-Atlantic flight, I'll switch to buying on price -- including for other work flights. (I have a 15% tolerance that I use to choose BA over United, which is usually cheaper.) That could easily be another £5k or more. Or maybe it won't be if BA is the lowest cost. What I won't be doing is spending an extra £5k(!) to chase gold.

I have run a rewards program (in a different industry). Pounds and pence are important for sure. But the mistake we made at first was rewarding too much spend we would've gotten anyway, and not doing enough to drive incremental spend. That's what I fear BA is doing here.