Imagine an app on the blockchain that emulates much of Facebook's abilities, with distributed processing, etc.
Yep. I have wondered if it is possible to lay an anchored skin over the existing apps and then add steem functions :)
The risk to blockchain-supported apps is that they may become islands of extremism and illegality and thus abandoned.
Some very will be but at the same time, there will be other applications that do manage their content in various ways that could be very mainstream. I guess it is about choice.
I'm not going to pretend to know the answers. These questions are very difficult and inseparable from censorship. A lot of people will have to do a lot of thinking about them.
I don't know either but I figure that is what we are here for, to find out if we can solve some of these issues.
Another problem with a Facebook killer is the risk of deanonymization. Most blockchain users are pseudonymous, like yours truly. FB is intentionally nonanonymous so you exactly whom you're dealing with. The FB killer would have to be implemented so that there's no risk of linking a user's real name with his blockchain identity.