Only a portion of the A320's and all of the A319's are at end of life. The 3 Rouge A 320's are 17 years old and there are Mainline A320's that are similar in age to the A321's. AC could certainly fly those A320's for many years. If you look at page 36 of the deck, there appears to be plans to keep them or park them based on demand. I suspect this unfortunately means a persistence of dissimilar narrow body cabins for a few more years.