Microsoft has said that there are no current plans to release a Blu-Ray drive for the Xbox 360. The company quotes only a 3 percent adoption rate of the HD-DVD drive for the Xbox 360 as the reason. Part of that is only because a format had not one when that add-on was released. This will be, at least, a short term victory for Sony and the PS3.
It would be poor business on the part of Microsoft if it did not release a Blu-Ray add-on. A Xbox 360 with a built-in Blu-Ray drive should also be in its plans as well if it wishes to maintain the "console war." The line-up could consist of a Blu-Ray add-on, a Xbox 360 with Blu-Ray (and WiFi) and the standard Xbox 360.