In my honest opinion, Google+ is never going to replace Facebook. All those friends and family members you have on Facebook, they’re not going to up sticks and move over to Google+ any time soon. It’s just not going to happen. Neither will Google+ become the new Twitter. Google+ posts lack the brevity and simplicity of a tweet. The format is quite different.
Google+ is not even a social network. As Google say themselves in the blog post announcing Google+, it's all about online sharing. They don't call it a social network, everybody else does. Google+ is essentially a publishing platform for sharing online content.
One service that should be worried about this new platform, and the speed with which it is gathering early adopters, is Posterous. For those of you who haven’t come across Posterous before, it is a website that lets you quickly generate blog style posts simply by sending in an email. Also, you can easily subscribe to other users' Posterous posts and receive a daily digest email of their latest updates. It has become very popular amongst bloggers, photographers, technology journalists, geeks, in fact the very people who are now flocking to Google+.
Posterous has several features as a publishing platform that currently give it the edge over Google+. Posts can be sent by email. You can apply themes to your posts. You can cross-post to Twitter, Facebook, Flickr and many others. You can use your own custom domain. You can sign up to a digest email of recent posts. Posterous has an API. The question is how long will it take Google to implement these features, or some very like them, as well as novel and unique ones, into Google+? The answer has to be 'not very long'.
Posterous also has the concept of groups, which allow you to invite people to see non-public content. So, just like Google+ Circles really, although with Posterous groups you can also allow others to become contributors. Whether Google+ would ever have a multiple editors option I’m not so sure about as a Google+ profile is all about you. Maybe it will be standard with Google+ business accounts.
Adding someone to a Google+ Circle mirrors the Posterous option of subscribing to their posts, one of the key features of Posterous, but adds more layers of connection. It means more, to both parties. Similarly, you can 'like' a post on Posterous, but that is trumped by a '+1' on Google+.
Posterous is, currently, free to use, but at some point it will need to monetise the service with advertising or premium accounts. Google+ is free and will probably always be so. When Posterous have to start charging or displaying ads then users, who haven’t already, will jump ship to Google+.
The reasons why Posterous should be worried about the exponential growth of Google+ are the same reasons other online services are worried: the built in user base, the deep integration with other Google services such as Gmail, the popularity of Android which will surely have more Google+ features soon, and, well, it's Google.
