I just recently changed from having an Aeroplan credit card to not. So on a flight from YEG to YVR with my 50k status I always was number one on upgrade list. Never was anyone ahead of me. (I never came across 75k or 100k on this flight and i have taken it 10 times in a year.) Without the CC, i was number 5. So let's do some simple math. The refurbished Alaska Airlines plane has 150 seats (138 Y and 12 J).

So let's assume those are 50k,35k, and 25k ahead of me, and below me on the non CC list. That is 2.67% of people on a plane have 25k to 50k status with a CC. Those without a CC, the total upgrade list is 10. So 9 people on the flight can be assumed to have 50k - 25k status. 6% of passengers have 25k - 50k status.

Assuming the number of Aeroplan members is 9 MM, that is 540,000 people who have at least 25k - 50k status. These are big assumptions, but given that AC doesn't release numbers of people at various status levels, this is as good as it gets.