AC has retired many of the 767's, and I've heard that the ETOPS rated A319's have gone over to Rouge.
The sad fact is that AC just doesn't have spare TATL capable aircraft to run these routes with so many MAX birds grounded. They've made the business decision that these are the best routes to cut given the fleet constraints. Yes, it stinks for my fellow East Coast folks, but we are used to sucking hind "nipple" (trying to use FT appropriate language). Westjet cut their YHZ-CDG and Icelandair cut their YHZ-KEF for the same reasons.