i have about a 200gb soft cap, god knows i have gone well over that some months.
assuming this is compressed data, and its compressed well, 1 blu ray quality movie, at 1080p could be as small as 4gb, and up to about 8gb for a standard length movie. for damn near indistinguishable form dvd quality, 1gb about, and this is from a novice encoder, you could probably get that down to 700mb
all that said, how many people are watching 200 dvd quality movies a month, 50 720p or 25 1080p?
now, as to bluray players... it is possible for ones that can update firmware to support this, i believe, i wont go into how, because it may be incredibly stupid on my part, but it may be possible.