Does Blu-ray HAVE to equal high definition?

[blu_sharpy]

As good a point as you make about putting a whole series on one disc, it will never really hit off. It would be completely pointless as there would be no upgrade and the consumer would just shrug off the product. People expect Hi-Def to be 1080p and to stick SD Content on a BD would be unacceptable.
To answer your question, yes we do see NON-HD content on BD's in the form of extra content (special features), but we will never see the main content in SD on a BD as it would be a complete waste of the companies time and resources.

Also ---- Putting SD content on a BD and upping the Bitrate would make no difference what so ever to the quality.