As someone who doesn't think pure spend-based makes sense, even for the airline, I would not have designed this program from scratch (or not). I think what D404 said is a part of that - I don't think it helps AC to go from one of the most rewarding programs for flying to one of the least overnight. That being said, I agree that the program was too generous relative to its competitors - off the top of my head Aeroplan is probably the program with the least extra cost to receive 100% of distance flown - and that a course correction was necessary, and points one and two above make sense to address as a result. The generosity of rollovers in particular is something that I have thought a bit more about (as someone who doesn't even have a premium CC because I neither fly nor spend enough to use that aspect of it). At the same time, I don't actually see what perks said cards now have beyond US/CA MLL access and allowing one to spend a lot (OPM, MS, yadda yadda) so that they don't have to spend as much with AC, for AC status. The math on the card simply doesn't work out unless you are both high status and can use it to reduce status requirements, and that's if keeping AC status makes sense (which in my opinion won't be over another *G status unless SE).

Points 3 and 4 relate to AC's market power. If AC only had WS to compete against, I can see how this analysis would make sense. But people have plenty of competitors to choose from (both flight wise and program wise). Is a mass desertion of lower-spending elites that definitely in AC's interest? People can reasonably disagree about this and I've said enough so I'll leave it at that.

With regards to generosity and timing of rewards, I also agree. Tier yoyo-ing is currently a legitimate strategy for maximizing eUps and perks, especially if you can stagger your flying such that you don't need higher status earlier in the year. I personally clear my eUps quite often when I want to, which clearly isn't ideal for AC (with the caveat that this also means their premium cabins aren't really that full - a 25K clearing on low Flex is taking up something that would have otherwise gone to a non-rev). Gutting the base number of eUps makes sense, especially for 25Ks, because R space way in advance is nearly nonexistent right now. But I don't feel that this magnitude is necessary for higher-tier elites, on top of which is the problem that everyone will currently start next year off with practically nothing (which is the one thing I could see them changing).

The real losers here are people who don't have a realistic program to pivot to from Aeroplan, which includes credit card 25Ks, which might not be lamented by many. But I for one cannot in good conscience recommend Aeroplan to a casual flier who asks which program they should use (and people I know can and do ask me about this) when they completely destroy the earn rate (1/5 that of PD).

Should also reiterate: 1x base earning rate will apply to most partner airlines even on AC ticket stock, which is a major restriction. UA also treats some of its partners as second-tier, but AC's first-rate section is literally limited to UA, LH Group and CM, and UA doesn't have a 6-fold difference for other partners. This will be extremely annoying for people who want to fly partners on 014 stock and absolutely brutal for people who are rebooked on other *A due to IRROPS (arguably AC should honour the original if they ticket it, will they?)