Called the other day about my Plat Charge.
Spoke to 2 people, no offer at all. Said they couldn't do anything because I was already grandfathered on a few things not available to new customers (e.g. lower Plat annual fee than currently advertised, with free companion Reserve card with the $400 travel credit included that's no longer available to new cardholders, etc).
All they could offer was a change to the Gold charge card, but it has separate annual fees, rewards fees, additional cardholder fees and doesn't give the free Reserve, so the cash saving in my circumstances wouldn't have been significant versus Plat, and with an earn rate less than I can get on non-Amex cards, so I can't see when I'd use it.
Instead, speaking to them about bonus points, I was able to get an upgrade on my QF Discovery card to Ultimate with 40k bonus points (has $450 annual fee but with $450 QF travel credit, so the points are basically free after meeting the minimum spend). Will probably downgrade the card after a year - really just wanted some bonus points.
Will likely keep the Plat for the next year now, but I'm mindful that the annual fee is very high to cover travel benefits, which aren't really being offered right now. If that isn't addressed in the next 12 months, I may as well move to Diners for points, and that's saying something!