A less oblique answer:

There might have been an AA policy worth detailing to you, but it's oneworld only which I guess excludes EI for now. If you can't get to EI (and even if you can), I would call AA. Not impossible they might reroute you DCA-ORD (or your ticket might be changeable) - they seem to be quite flexible on domestic IROPPS. But expect to have to make your own way from IAD to DCA, and the connection would still be at your risk.