Cactus Game Design Message Boards

Yes, he's still discarded.

To expound, since Egyptian Archer's ability was never interrupted (Wonders Forgotten has no interrupt on it), the full ability carries out when the battle is ended by WF.  If you want to save your archer by playing WF, you need to interrupt/play next with Egyptian Horses (Edit: or Swift Horses) in some manner.

For further clarification:
   Egyptian horses intentionally was to designed to keep Archers from interrupt/play next so that wonders forgotten wouldn't save them from discard (Swift horses still can because of interrupt/play next).

Reason: they didn't want to have two brigades that could cause mass damage (benefit) with no cost. (Pale Green can do this with their Archers, Horses, and Forgotten History.)