Well with Google Music offering free storage for music, and Picasa offering very affordable picture storage, I would venture to say it shouldn't be an issue. I believe Amazon offers some limited free storage as well, and I've heard very good things about Dropbox on Android. I'm sure there are other solutions as well, you just need to look around a bit.
So unless you insist on carrying 10 movies and 3 days worth of music on your phone, I would think you'd be ok. With that being said, nobody uses their device in the exact same way as the next guy. I'm coming from a Palm Pre Plus with 8G of storage, and I never really had that much of a problem managing data, but YMMV as they say.