My guess is you will see Blu ray in the xbox 3 (whatever the fook its called), sony may own blu ray, but a licensing cut of every xbox sold in the next generation would be a very tasty pie indeed.
But Sony will literally cutting their sales at the same time. The only thing telling the PS3 from the apart from looks and controllers is the blue ray capability. So what Sony will have to do is think of a way to stop the Xbox taking over completely but still give them blue ray capabilities. if they want to make as much money as possible (which everyone does)