Why would any company like facebook accept Bitcoin? I understand that we are convinced about Bitcoin here at this forum, but that is still very little and has no influence whatsoever on big companies accepting it. So what would be the incentives?
If enough of their users ask for it, they have nothing to lose by integrating it. They wouldn't have bought instagram otherwise. There's no particular reason for them to champion it so they'll probably be laggards but enough demand may bring it along eventually.
Mass users are only aware of Bitcoin because they have heard of it in the news about coins stolen from Mt. Gox, Silk Road, etc. I think people in this forum tend to project their way of thinking as the main stream thinking, which is obviously not.
So I agree, that Bitcoin may be only added if there is enough pressure from the users to do so, the question now is, whether such appears? For that, it is needed to have a bit more positive picture of Bitcoin in the main stream media, first.