I see nothing exciting about learning that old RDs that are no longer made will work with something newer, or vice-versa. The smartest thing you can do is upgrade to the latest parts when you're able to and move on. Campy 11 speed came out back in 2009. I changed all my bikes to 11 speed shortly thereafter. The only reason I have an older 10 speed Campy RD coupled to an 11 speed shifter, is I quite cycling at the end of 2010 and the bike's been sitting since then. I found a simple mod that allows the Campy 10 RD to work with an 11 speed Campy shifter. I rode several thousand miles with that combination. The bike now works nicely, mounted on a hydraulic resistance trainer, to use for knee replacement rehab. I get the other knee done in November, and it will continue on with valuable rehab service.