They said in a post a while back, don't remember where, that they "have no plans to release the expansion for 360/ps3," cause they're concentrating on their ps4/xb1 versions. Doesn't mean they wont do it though.
At Blizzcon they said they were concentrating on the PC and PS4 versions first. They had both platforms (PC/PS4) there with playable demos. When I asked a developer directly if they were planning on coming out with an XBox 360 version, the answer I was given was: "We don't have any news on that front at the moment." That was November 9, 2013.
It seems pretty likely it will come out for 360 eventually. Blizzard probably made some kind of exclusivity deal with Sony to keep it on PS4 for a month or so. Also, the console versions, despite all the changes from the PC versions, they very clearly have extra space in each hub world for a third vendor, and since ROS adds a new vendor I would say they planned in advance for it.
Vanilla Diablo 3 for PC also had that hub for the 3rd artisan... and this is the code they ported from PC for the last generation consoles. This doesn't mean anything about porting to to the 360.
As for the exclusivity deal, I would NOT be surprised if Blizzard either doesn't release the expansion on last generation consoles at all.. or they do but don't give the Ultimate edition to XB1. (Think Injustice).
This game will be ported to consoles, the original game was entirely design for consoles in the first place... 4 player very few hotkey buttons, it was made with the intention of easy port to console behind it. Just gona have to wait for RoS as a DLC package for Xbox.