Air Canada did actually despatch a replacement aircraft to MAN late yesterday. However, that B763 (C-GSCA) got as far as the Montreal area before returning to YYZ, presumably with a problem of its own. C-FOCA is expected at MAN around 11:00 today, but I think this is the aircraft planned as Sunday's regular flight. So there may be two Air Canada B763's departing MAN for YYZ today.
I love the bit where a passenger claims that the flight was cancelled "because the pilot was tired". One way to summarise going out of hours, I suppose!
Bagso ... I know that your comment was made in jest, but MAN-YYZ is provisionally due to switch back to AC Rouge from 25/07 anyway. Your wish should be granted tomorrow!