These aren't just technical questions—they're philosophical ones, too. Twitter apparently has plans to become the world's largest online service, aiming to eventually connect a billion users. Let's assume that's possible. Is it desirable? A single online service responsible for one-sixth of the planet's chatter would be a huge target for terrorists, governments, and anyone else. "What if prostitutes are operating on Twitter? What if a major act of terrorism is organized using Twitter? Would there be pressure to shut it down or greatly control what it's used for?" Winer asks. If you think that's far-fetched, Winer asks you to consider the atmosphere after 9/11, when some people were calling for the Web to be monitored or shut down. Nothing ever came of that because it's too hard to shut down the Web or e-mail. "Twitter, which is fully centralized, would be easy for a government to control," Winer writes.
Winer, one of the creators of RSS, proposes using Web syndication as a replacement for Twitter. His idea, called RSS Cloud, is technically complex, but it boils down to this: When you send out an update, it'll go to a set of servers in the Web cloud. The servers will keep track of your subscribers and alert them that you've updated. The key difference between this system and Twitter is decentralization—not everyone's updates are kept by the same company or on the same servers. The system would work much like RSS does now: You can subscribe to lots of different blogs or podcasts, but those feeds are actually hosted all over the Web; some of them may go offline from time to time, but the whole thing won't collapse all at once.
Several different groups are working on technologies that complement Winer's vision. (Here's a good Wired article that describes several of them.) In an insightful blog post, Anil Dash recently described these technologies as creating what he calls the "Pushbutton Web." The Web today is a "pull" medium—you (or your RSS reader) have to keep checking a site to see if it has published new content. That process is inefficient; it's like looking out the window every five seconds to see if the paperboy has dropped off tomorrow's issue. Pushbutton technologies—including PubSubHubbub (seriously, that's its real name), an open protocol developed by programmers at Google—let sites notify you whenever they've been updated. This is like the paperboy ringing the doorbell when he's left a new issue. Google recently built PubSubHubbub into Google Reader, so now when you click "Share" on a blog post that you like, Reader instantly notifies the other sites you're connected to. You can share a post from Reader, and it'll show up on your Friendfeed—and maybe on Facebook and Twitter—immediately.
Twitter hasn't embraced these open protocols; its business interests lie in keeping everyone under the same roof. But as technologies like PubSubHubbub proliferate around the Web, with companies like Google, Facebook, and others embracing them, real-time Web updates will become the norm. It won't be hard to build competitors to Twitter—systems that do as much as it does but whose decentralized design ensures that they're not a single point of failure. Winer envisions these systems coming up alongside Twitter—when you post a status update, it could get sent to both Twitter and whatever decentralized, next-gen Twitter gets created. If these new systems take off, Twitter would be just one of many status-updating hubs—and if it went down, there'd be other servers to take its place.