I would only point out here that the assumption that there will be an "XL" version of this game isn't as rock solid this go-around. While it's true WB has published "GOTY/Ultimate" editions on-disc for Injustice 1, Mortal Kombat X, and prior games, the landscape of physical retail releases is radically different now.
And recall WB released Injustice 2 with an Ultimate Edition that included all DLC.
WB has been one of the more notorious companies that is pushing DLC/microtransactions of late so it's not unreasonable here to think here that even a retail GOTY edition might instead just include a vanilla disc and the codes (in short, a reprint of the ultimate edition in a new case).
WB didn't bother with a GOTY edition in North America for Arkham Knight, and in Europe, did exactly the above. Also think WB will probably do the same with whenever the final DLCs come out for Shadow of War.
This would follow the Capcom model more closely (see Arcade Edition), and again, reasonable to think WB is looking at its competitor's model, and thinking it's a way to save money on the "new" retail release.