Bit.ly has to worry about Twitter, which I assume is where most shortened URLs are created, and where most are dereferenced. That's probably why they took the price off Bit.ly Pro, and gave the features to everyone for free.
Of course, they had to do this, because Twitter itself is now offering almost everything Bit.ly already offered for free, also for free. It's unlikely that Twitter will match all the features of the Pro version anytime soon, so Bit.ly has a reason to exist.
What if Bit.ly were to actively get on the side of the user, eschew any form of lock-in, and perhaps for a price (let's be fair) give people the freedom to leave Bit.ly at any time without breaking any of their previous links, and keep their own domain.
It's technically possible to do this, if the user has an S3 account. And there's nothing hard about setting one up. You can use the same Amazon account you use to buy water skis, toothpaste, bike helmets and bottled water.
Long-term I don't think there's much hope that Disqus will hold out against Facebook, unless, again, they actively take the side of the user. What if they automatically deposit the text of every comment, in JSON perhaps, or XML (or your choice) in your S3 bucket. I keep using Disqus as an example here. I doubt if they'll ever do it. They're not the kind of company that goes first, it seems.
Which is funny because both Bit.ly and Disqus did go first, early in their lives. Unless I'm missing something have they made so much money or other kinds of success that they can afford to stop pushing the envelope of what a tech company will do to gain your loyalty?
BTW, one of the things I, and so many others, love about Dropbox is that it's all about making our data more accessible to us. You never have to think about how to get your data out of Dropbox. It's sitting right there on your hard disk, reminding you why you love them. Because their product empowers you without locking you in. You could even figure out a way to synch Dropbox with their competitors' products without giving up Dropbox. We need more services like that. (I gladly pay them $99 per year because their product is so useful, and makes me feel powerful instead of like a hamster.)
I've been around this block a lot of times. At some point the users are going to want to know who are their friends and who aren't. For a small company trying to make it in the midst of giants, when that day comes, if you've been trying to act like the big guy you aren't, it's off to the glue factory! :-(