Every enhancement from the airlines has made me more and more of a free agent flyer and every enhancement from the banks gets me closer to the tipping point where I'll be better off switching to a low-fee credit card without foreign exchange fees and quitting these games.
With Amazon gone, the Accor membership being "enhanced", the dining credit (that was already a nice-to-have but hardly a "wow I really adore this" for me) due to expire as well this year, and now this --- I'm definitely getting there. If I weren't fortunate enough to have held the Plat long enough to still get the additional $400 TC that came with the free Plat Reserve card before they enhanced that away too, I'd probably already be there...
And all that before you even consider the potential degradation in some of the other benefits, e.g., I find the Accor Plus rates not as good as they were a few years ago, the genuine deals that could be come by on the Fine Hotels/Hotel Collection are fewer and farer between, ditto discounts for premium airfare booked via AMEX Travel.
As for "where else will people go?" -- I imagine things are going to get worse across the board, but AMEX's Plat/Centurion fees are multiples higher than other products focussed primarily on points earning and the additional benefits meant to justify AMEX's multiples are being enhanced down/away too.
Between this, QF's devaluation and VA's devaluation + obliteration of status-earning for most status-holders, 2025 has been quite the doozy for Australian frequent flyers. Nowhere to hide.