I believe Twitter would have a much brighter future, Facebook too, if they trusted the web. If they let every bit of their service be replaced. That would force them to compete based on service, value and features. Now they get to be lazy and that's fine for a while. But the crazy chaos of the web will eventually do something exciting that you won't be able to match on Twitter. Had they been more trusting they would have guaranteed that whatever excitement comes along would automatically include them.