China Eastern don't fly to Europe from PEK and I would be very surprised it was any other mainland China service.
I wouldn't rule out China Eastern to Shanghai.
Firstly, Air China and Hainan are really stealing the march on China Eastern at PVG. Hainan have opened SEA/BOS and applied for BRU, while Air China have applied for SJC/MAN/BCN to start next summer. Due to the one airline rule, this is severely limiting MU's scope for expansion to realistic destinations, therefore, MU may want to try for DUB before HU/CA get in on the act.
Secondly, a routes online article stated PVG was actually a bigger market from MAN than PEK, now, I don't know what the DUB-China market forecast looks like but I don't suppose they are too dissimilar from MAN in terms of flows, so, it's not beyond the realms of possibility that PVG could come before PEK at DUB.