FB didn't even need to do anything, just their existence and networking abilities is enough to make alternatives unviable.
I do wonder what we will do in the long term as most places are centralized. Google and Apple for a mobile OS, FB (or FB properties) for social networking, there's Twitch for streaming, YouTube for video hosting.
These days, the chances of competition are (IMO) impossible due to the sheer size and influence (and power) of these mega giants.