The not-so-shock announcement was made earlier today by admin Yorick on the official Mortal Kombat X forums:
After months of development, Warner Bros. Interactive Entertainment has come to the regrettable conclusion that we cannot release Mortal Kombat X for PlayStation 3 and Xbox 360. Please know our teams worked diligently to meet the quality standards set by the current-gen versions of the game. We were not able to get the PS3 and Xbox 360 versions to the quality expected of a Mortal Kombat game and are very sorry for not being able to deliver the products as originally planned.
If you pre-ordered Mortal Kombat X for PS3 or Xbox 360, please go to the retail location where you pre-ordered the game and you will receive a full refund.
Released for PlayStation 4, Xbox One and PC back in April, the PlayStation 3 and Xbox 360 ports of Mortal Kombat X have seen numerous delays with many doubting their eventual release. Limitations with older hardware is the most likely cause of their cancellation, as well as a shrinking demand as gamers move to modern consoles.