darthspudius: Seems illogical without the first two. So, I assume those two are on the way also.
Different publisher, so no guarantees.
Shenmue 3 was made on a license by Sega to the original creator, and Deep Silver stepped in to publish it.
Just like Streets of Rage 4 and Panzer Dragoon, Sega's cool with letting other devs make games for its IP, as long as it doesn't have to incur any costs themselves. But that doesn't mean they themselves will be jumping on the GOG train any time soon- at least we can't take this as any indicaiton.
Not that I'd say no to having the Yakuza games here or anything. Premium single-player only content belongs on DRM-free stores.