This is not a question that can be answered in a span of less than a decade.
Yeah, you're right, but it's an interesting one to ponder.
IMO, twitter itself is a fad, but only because it's somewhat revolutionary. It's becoming a collectively conscious entity, much like the entire internet. Twitter is around because people want to know what others are thinking as soon as they are thinking it.
Twitter will die when we come up with a more efficient form of telepathy.
Twitter will die when we come up with a more efficient form of telepathy.
Or, the novelty of being continually flooded with pointless and trivial information wears off.
And this blogging thing should bite the dust pretty soon too, right?