Let's not be so pessimistic, SxII was retrocompatible with the 360 (and also not all games were).
The great news with this, however, is that Xbox One backward compatibility works differently. It reads the game disc, but never uses the information off of it. It just checks to see if it's genuine, then proceeds to download the re-packaged game from the Xbox Live servers and install to your HDD. If you own the physical copy, then it's just a key.
I say this is great news, because 99% of all Xbox 360 games playable on Xbox One are sold directly through the Xbox Live Marketplace (really only ME2 and ME3 aren't... because EA wants you to subscribe to EA Access if you don't own the discs), and Shenmue's not been available digitally before.