Sony has projected the lifespan of the BluRay to be ten years. The DVD did a little better, but media format development has increased in the last decade. With many companies vying to produce the next disc format, and frankly probably the last disc format. Once you get into terabytes of storage there just isn't going to be a demand for anything bigger. That is more then sufficient to store entire movie, game, and music libraries onto a single disc.
Right now we are coming into the territory of holographic media. Which should be fully backward compatible with all of the previous formats. Given that Microsoft has spurned BluRay it is probably likely that they are already involved in one or more joint ventures to implement one of these formats. Probably with General Electric which intends to release their new format in 2013. Microsoft probably intends to jump the current format generation entirely. Which would allow them to have a very obvious hardware advantage, and to seriously pressure the BluRay format.
Microsoft seems rather earnest in not supporting BluRay, and has actively searched for alternatives. Supporting a newer format seems to serve their interests. Not only that, but full backward compatibility would mean that they wouldn't have to make a actual choice. It is easier to support a legacy, because it isn't a validation. Supporting old or outdated formats is to be expected.
So yeah the NextBox will probably play BluRay movies, but it probably will not be using a BluRay drive, and there is just no reason to expect that such a drive would become obsolete for decades. Well until something supercedes television as the conveyance.
