Three years ago Delta introduced minimum spending requirements for elite status. The revenue requirement was essentially set at 10 cents per mile — e.g. $2500 for 25,000 mile status, $5000 for 50,000 mile status and so on. That was a big conceptual move, but one with limited effect in practice.
However revenue-based requirements for elite status have now spread internationally — to North of the Border. Air Canada is clearly trying to cull their elite ranks, something consistent with their past stated attitudes towards elite frequent flyers.