That sucks, for the newest 5000 series units were only from 2004. That'd be like the MTA scrapping some R142/As. Could have used some for Work trains. If they retire the 6000s next, then they really would be foolish. The 6000s IIRC are Metro's second most reliable cars.
I know that #2506, #2523, #2532, #2553, # 2580-2597 and #2599 are all retired. Do you know if any C40LFs are left on property? I know WMATA had like 4 or 5 2000 Orion VIs @ CET a few months ago. They need to have a museum fleet of buses too.