Spotify is successful because its giving people what they access to what they want. So long as they continue doing that they can be successful so long as they can also find a way to make a profit at the same time. However, they have attracted a loyal following for a good reason.
Yes, I believe that Spotify will succeed. Actually, I believe that so far it has already succeeded, as I as well as millions of others already use Spotify. It is a new and unique way to interact with music, and it is something that will hold the test of time, unlike many of the recently failed startups that have hit the internet.
Years ago we had napster. It had too many flaws and songs that were not completely downloaded. Spotify is strong and so much better than the other music downloads. As long as it continues to grow, it will continue to succeed and create hours of the newest music, as well as the old.
As a Spotify user, I personally cannot see how it would not succeed. I used Pandora for a couple of years before signing up for Spotify, and I find that Spotify far superior to Pandora. It has tons and tons of free music for anyone to listen to. How could Spotify not succeed?
Spotify offers cheap music streamed directly to your computer or smartphone. Combined with a wide variety of available music, it's hard to imagine that Spotify won't experience at least some level of success. The audio quality isn't the highest. The artists who create the music are receiving a far lower royalty for their works than from other sources. But that doesn't matter to the music loving public. Give us our music now and for nothing!