I booked SNA-PHX-MCO in economy. PHX-MCO complimentary upgrade cleared a few days prior to departure. SNA-PHX did not clear.
Woke up on day of flight to an AA app push notification offering Dynamic Reaccom due to a delayed SNA-PHX. AA's app offered instead SNA-DFW-MCO, both legs in domestic F. That worked out really nicely!