Yes, Microsoft will market a Blu-ray addon or maybe a built-in. Toshiba will perhaps build it for them.
Most customers don't even know what "BD-J" is let alone caring about it. Besides, that is a old battle.
Microsoft is trying to buy Yahoo now and obviously that is more of a mainline concern. They will be wanting to shore up the XBox 360 with an HD solution to replace the add-on.
I also predict that Nintendo will have a Blu-ray drive in the Wii. They have said that they would come out with a model that supports DVD, but I think they will look at the hidef situation and decide that it must be Blu-ray.
These consoles are going to become more multi-purpose. With Blu-ray, the Playstation is somewhat ahead on this point, but Microsoft is ahead on their download infrastructure, which Sony is now adding for the PS3.