Pokemon is all about transmedia and marketing. The TCG sets promote the other aspects of the franchise. For example, the Hoopa movie will be released in Japan next month, hence Bandit Ring focusing on Hoopa. America has to take time to dub the Hoopa movie, so the set meant to advertise it (Ancient Origins) won't be released until around the time the Hoopa movie will premiere here. If they were to release the set here in America at the same time as Japan, the marketing potential would be lost. This is why in the old days, whole sets would be reordered in America (like EX Legend Maker being between two Delta sets) so that the release would coincide with the release of the movie it was meant to promote (Lucario and the Mystery of Mew).
Also, we've known for almost 15 years that sets are printed months and months in advance and probably planned around a year or more in advance. I wouldn't be shocked at all if they've already sent the XY BREAK set to the printers.