I applied for an eUpgrade on a YYZ-YUL flight. Purchased seat is PY. Now the flight changed and I am offered to select a different flight. However, that flight is the only one with PY for that day.

In the event I select a different flight I would forego my PY seats, but would I also forego my priority for eupgrades? Would I still be at the top of the list given my original ticket was for PY?