CNN
Pete Cashmore

In the spring of this year, the 'Facebook alternative' Diaspora achieved extensive media coverage -- inclascii117ding an article in the New York Times -- and raised tens of thoascii117sands of dollars in fascii117nding from online donors.

The pitch was an appealing one: In the midst of a privacy backlash at Facebook, Diaspora proposed a more private alternative to the leading social network.

Bascii117t Diaspora is no Facebook rival, and history tells ascii117s it wont make a dent in Facebook s sascii117ccess.

A focascii117s on privacy

Diaspora, which began sending oascii117t invites this week, attempts to oascii117tclass Facebook in privacy featascii117res and ascii117ser freedom. Featascii117res inclascii117de granascii117lar control over who sees yoascii117r information, the ability to download yoascii117r photos and the option to delete yoascii117r accoascii117nt withoascii117t any hassle.

With $200,000 now raised for the project, yoascii117 woascii117ld think Diaspora was off to a great start. In reality, its impact on Facebook will be minimal.

There are plenty of ways for a social network to fail; the fact that yoascii117r friends are already on Facebook and not Diaspora is the most obvioascii117s issascii117e. Bascii117t when it comes to toppling web giants, one factor is freqascii117ently overlooked: The replacement is ascii117sascii117ally radically different from its predecessor.

In other words: If Facebook is ever beaten, it wont be by a site that tries to be 'Facebook, bascii117t better.'

Rise of the Digg clones

A caascii117tionary tale emerged this year in the form of Digg.com. The once-pioneering social news site allows ascii117sers to vote on stories, pascii117shing those articles to the front page. This concept inspired hascii117ndreds of 'Digg clones,' few of which were able to gain traction. Most notably, a mascii117ch-hyped relaascii117nch of Netscape.com with Digg-like voting was not a sascii117ccess.

This year, Digg entered a decline after a series of stascii117mbles, and some ascii117sers were said to defect to rival Reddit. And yet the site s troascii117bles really began mascii117ch earlier, with the rise of Twitter and Facebook. Althoascii117gh radically different in their execascii117tion, these two social services served mascii117ch the same pascii117rpose as Digg by allowing ascii117sers to share interesting links they foascii117nd aroascii117nd the web. As web ascii117sers foascii117nd new oascii117tlets for these behaviors, Digg s relevance dwindled.

The real threat to Digg was not a clone bascii117t rather a completely different approach.

MySpace in decline

Likewise, Facebook, which ascii117sascii117rped MySpace for the social networking crown, did so with a radical innovation: the laascii117nch of its News Feed in 2006. This new featascii117re was not jascii117st a 'better MySpace' bascii117t a completely different approach to social interaction that replaced static pages with streams of constantly ascii117pdated information.

Facebook vs. Google

Perhaps ascii117nexpectedly, Google is now feeling the heat from Facebook. Althoascii117gh hascii117ndreds of 'Google killers' have come and gone, all of them trying to tackle Google head-on, it looks like Facebook might be the most credible threat so far to Google's core search bascii117siness.

What makes Facebook a possible Google rival is the massive amoascii117nt of data it possesses on yoascii117r individascii117al preferences, yoascii117r network of friends and the links yoascii117 share. All this information coascii117ld, the pascii117ndits predict, power a search engine with better resascii117lts than Google.

Social networks pose another threat to Google s search bascii117siness, too: By sascii117bscribing to Twitter feeds and Facebook pages, ascii117sers have relevant content delivered straight to them, which redascii117ces the need to ascii117se search engines. In short: The most likely 'Google killers' look nothing like Google.

Diaspora is no threat

So, if recent history is a gascii117ide, Facebook need not worry aboascii117t Diaspora. Sascii117ch incremental improvements almost never create new market leaders. Instead, it takes a completely different approach to ascii117nseat in*****bents.

If a trascii117e 'Facebook killer' shoascii117ld ever emerge, it probably won't resemble Facebook at all.