I don't know if it still applies, but used to be airlines had to report delays of more than 15 minutes. A trick AA would do is move the flight 10 minutes at a time and avoid having to report.

The problem with using the inbound flight as a guide, AA could choose to substitute a different plane and take off before the originally scheduled aircraft lands. This is especially funny when it's a continuing leg of the same flight! Ooops! You've missed your connection.

Bottom line, anything could happen, so be there according to original schedule and hope they get something going.