Remember that the video output of the xbox and the xbox360 is determined by the type of plug attached to the unit. The unit itself has a proprietary plug. Getting Component, S video, RCA, HDMI or DVI is just a question of releasing another cable adapter. If Microsoft decided there was not enough demand to produce a first party HDMI/DVI cable a third party company could produce it just as well and most likely will. For example, the xbox does not have a VGA connector made by MSFT (there was not enough demand to warrant it) but there are connectors for this made by other companies.

As for HDDVD and BlueRay it will NOT be in Xbox 360 because it will does not and will not exist for the xbox360 timeframe (November 2005). Microsoft has stated that they are flexible and would include it once it is available (they are also very wary about what will happen between HDDVD and BlueRay). Sony has touted BlueRay but admitted to developers (in private less publicized events) that this may change depending on the state of the market for the March 2006 time frame. At this point joining either camp is probably a bad idea and it makes sense to wait until the dust settles (VHS vs. Beta war comes to mind).