IIRC, the 787 comes from the Shanghai flight most days, and has been delayed frequently since May. I'm surprised AC hasn't retimed it to be honest - I think I've seen it been on-time once in the past few weeks.

Per AC's delayed flight service, 4-hour delays let you switch flights for free and get a food voucher, but given that this is the last flight of the day not sure how beneficial that would be. When I was delayed 3 hours last year from YUL I didn't receive any compensation, but I was on an Aeroplan reward, so not sure if revenue passengers got a 5 or 10% off discount code.