Ben S,
Firstly, thank you for giving me at least some hope that YYT-LHR year-round might come back.
But on the Tango vs. Flex thing. I just booked travel to LHR next month. Delta between Flex and Tango was $500. I can't justify to my employer that $500 is worthwhile simply to get 100% AQM - as there is no other benefit to me given the Copay required to e-up which my employer won't pay & that the "Flex"ibility of the ticket is limited. So I get less AQM for my TATL travel which likely drives me down a status tier or maybe two for next year. AC gets to save money on providing me the status benefits that, previously I earned through 80k or so bum on seat miles with AC.
Difficult not to be upset about that as a customer and one that, as I've already said is largely captive for TATL travel at least. So that reduces my loyalty to AC further, prompting me to consider alternatives for my domestic & US travel. So I go from being a happy AC customer, spending $70k per annum or thereabouts to a disillusioned (former) mid tier. I know I am not alone in this.