I truly believe they are opening a gap that others could exploit. Microsoft, so late to this party, with their userbase and technical know-how, with a lot of their ill deeds from the past forgotten or forgiven. If they decided that they are going to do it right, and not try to exploit users, they could become a threat again. I wonder if they are capable of this anymore though.
Or, reddit, with their substantial userbase of young, technically advanced, and influential users - if they could figure out the scalability issues, they could launch a youtube competitor, for example, and LOTS of people would move there very quickly, even if it is not as good, because they are (so far) known to be pure, whereas google has now proven that is is not pure, and dishonest (do no evil).
It's certainly not easy, but my point is, it's a lot easier when influential and vocal technical users have turned on you, and the degree to which they've turned.