The past few days I have spent some time reading all the comments and, of course, forecasting the effect on me.
First, like others have noted, I can see why AC made the change, and it does appear to make business sense for them. For a pure flyer (e.g. no premium CC) its terrible as the spend requirement has increased 50% for each tier. But some have had the spend without the SQM, so its a positive in that case.
Based on my 2025 travel (85k SQM / 22k SQD) and spending pattern, I would be right on the bubble for 2027 SE qualification after CC spend and rollover conversion. (I will requalify for 2026 assuming a strike does not interrupt my scheduled travel). I have the ability to direct some more spend to my Aeroplan card to gain some SQC, and/or another domestic flight would do it given the 4x multiplier (which I initially forgot about). I don't really frequent any of the everyday partners other than the odd Uber ride, so those are useless to me. I am more optimistc about requalifying for SE than I was a couple of day ago.
What really bothers me is the transition year - 2026. I assume most of us who plan things out made decisions based on the current benefits being in place for 2026 - starting the year with an allotment of e ups, a status pass, etc. The ability to gift status is one of the worst IMO. As some else noted you can't gift 50k status until after you have requalified for SE. In my case I (we) made the decision for most of Mrs W's travel to be reward travel this year (she is currently 50k) and I had planned to gift her 50K next year. Any volunteers to have the discussion with her when she has no status next year?

(And I guess the loung pass gifting thread will be dead after this year.)
And as already noted, the MM program is significantly devalued in addition to being harder to achieve. After providing AC with loyalty (and money) to achieve MM status, 50k (or above) was a nice perk, especially for those who may be nearing retirement and/or travelling less. While it still provides lounge access (including *A access) and a few other benefits, there is not much else unless you continue to spend with AC . Terrible downgrade for such a milestone.
For me there does not appear to be a viable alternative. WS does not have a viable program (and based in YYC it would often be more convenient). The other day I did a (admittedly small) sample of a couple planned 2026 TATL trips. In each case WS J low was 50% more than AC! Hard to believe, but with smaller cabins maybe they can stick to that pricing? And with travel split between TATL and domestic KLM, etc makes little sense. So I will probably continue to fly AC and complain here on FT!