It depends on what you call success.
If you rate success as sharing the spotlight with DVD and digital downloads, then yeah it will be successful.
If you define success as having the same market share as DVD at its peak, then no blu-ray will never achieve that level of success.
Well, BD consortium may well be content with this "second choice" success, as it would happen in a very enlarged market, so even not reaching DVD's share, it could possibly exceed its absolute numbers.
Anyway DVD is getting its maximum spread during the last 2-3 years (even more on PC's, as prices dropped first under the $100 psychological threshold), since commodity priced players first, writers after, started appearing. In the same way BD won't get its best until these same conditions are satisfied. But this is about drives, blank media will gain the same success as soon as they get cheap, because their capacity is a clear advantage, OTOH recorded contents could struggle more if not heavily helped by the majors, as as long as a consistent price difference will exist between the same title in BD and DVD, most people will buy more expensive BD versions only for the best movies and/or those with heavier use of effects, or the best photography, etc.