Not sure who would want them, there are more than a few RDCs for sale right now, for as little as $45,000 each. There's a company in Canada that has a stockpile of them and is willing to sell them "as is" or fully rebuilt with new engines and electricals...virtually no takers.

I could see TriMet buying them for WES (since TriMet has a blank check policy for anything involving trains) but that's about it. I doubt any of the tourist railroads in the area have any interest in running RDCs. Although for the Mount Hood Railroad it would be much easier to run the RDCs through the switchback, and their existing car fleet leaves quite a bit to be desired (choice of east coast commuter cars with 2x3 seating, old early 1900s cars with no A/C, or a top heavy dome car that tracks very poorly on the jointed rail).