Flickr failed because they sold to Yahoo which was bad place to end up. But a successful Flickr would look a lot like Instagram

Del.icio.us is the same story. Good product ahead of its time, bought by Yahoo and died. Could have been Pinterest.

Fair point, there's a good chance we'd be living in a techno utopia right now if someone was able to go back in time and prevent Yahoo from murdering so many promising startups. Conversely, if Yahoo had just spent the relative pocket change that Google was asking for back in the day perhaps we'd be living under the oppressive thumb of a trillion dollar market cap Alta Vista.