Allow me to make a bold predication - the App.net will be done in a matter of months. Even if it becomes absolutely free.
The reason is Tent. If Tent drops the ball and doesn't fully execute the idea, someone else will. Their idea is bigger, better and far better maps onto the interest of various 3rd parties (such as hosted service providers) that wouldn't hesitate to support it. Commoditizing the social services is a great idea with balls and vision. Creating a paid Twitter clone is not.
The reason is Tent. If Tent drops the ball and doesn't fully execute the idea, someone else will. Their idea is bigger, better and far better maps onto the interest of various 3rd parties (such as hosted service providers) that wouldn't hesitate to support it. Commoditizing the social services is a great idea with balls and vision. Creating a paid Twitter clone is not.