I think there is literally 0 chance for another Facebook. Google tried with Google+ - billions of dollars, millions of man hours by brilliant engineers, crazy bundling strategies by Google. Is Google+ another Facebook yet? Nope, not yet, maybe not ever.
Your strategy has merit, but simply making another Facebook is not going to work now (It would have back in Myspace days). Now there is not an untapped market of people - almost everyone has things vested in social media companies.
1. Companies need either to do better then Facebook (Once again Google tried. Do not get me wrong, there is a fair chance that eventually Google+ will prevail, but very few projects have full might of Google paving their success.) 2. Or have different punchline than Facebook does to attract users (This is what Snapchat did). *typoed
Your strategy has merit, but simply making another Facebook is not going to work now (It would have back in Myspace days). Now there is not an untapped market of people - almost everyone has things vested in social media companies. 1. Companies need either to do better then Facebook (Once again Google tried. Do not get me wrong, there is a fair chance that eventually Google+ will prevail, but very few projects have full might of Google paving their success.) 2. Or have different punchline than Facebook does to attract users (This is what Snapchat did). *typoed