Hi all, my question is about last minute flight changes.

With the seat sale I got YOW-YYZ-BWI for $157, so I bought 3 of those all for within the next month. Great deal, but I'm going to sorely miss my YOW-DCA direct! I feel like over the winter I could get YOW-DCA for >$200 all the time, it was no big deal; but now it wasn't even part of their seat sale.
Q: When I get to the gate, if there's still space on the YOW-DCA, you think I'd have a chance at getting on the flight? I'd prob pay $50 to trade any of the three in.