Pafl: Good question ! Of course a chess-like endgame is impossible in Extinction, but we could choose to call endgames all positions where both camps have only unique pieces except of pawns (that is, KQRBN v KQRBN). I didn't reach any here yet, but it doesn't seem an unlikely issue at all.
Now, many of the positions just after the last piece trade will probably be either simple forced wins, either dead draws with all pieces having to stay on their posts in order to avoid a breakthrough. Has anyone played an interesting "endgame" here ?