So when will Twitter go the way of Digg and geocities?

"Coke talks about Coke. Pepsi talks about Coke. It's good to be Coke."

When people stop talking about Twitter in the same breath they discuss any other social network is when Twitter dies. Until then, good luck.

I don't know about Digg or Geocities. It might go the way of cosmo.com though. By this I mean it might get taken down because it's an unprofitable privately held business with no clear path to profitability.

If it wants to remain an ad supported platform it has a significant catch-22 to overcome: it can't attract advertisers without hiring moderators, but it can't hire moderators without attracting advertisers.

Its subscription model has been unsuccessful so far, and the revenue it generated has come at a cost to the overall quality of the platform. If Twitter continues to go down the path of user payments, like adding micro-transactions for example, I could see it going the route of Everquest. Where it will stay alive indefinitely thanks to the contribution of a small group of whales, but will never be relivent in the social media landscape.

When Youtube decides to stop locking iron balls on a chain to both ankles.

Patience.