Where did he ever have to actually show this quality of keeping up with competition? So far there simply hasn't been any "next big thing" that facebook would ha

Where did he ever have to actually show this quality of keeping up with competition? So far there simply hasn't been any "next big thing" that facebook would have to actually be afraid of. They have so incredibly many users, that alone makes them de-facto untouchable as of now. Even google plus could not change that. All of this might change some time in the future, just like it did for myspace and there was nothing they could have done about it if you ask me.