Happens all the time with legacy airlines. When I was based on Saskatoon I would regularly book trips to the US on the afternoon flight on United to Denver or Delta to MSP. If either one cancelled or the delay was significant enough to not be recoverable the same day the normal response was to move me onto the other guy. I had the same with AC and European airlines when they can't reroute on their metal and get me to the destination the same day.