No it is not...Ideas like this generally don't scale, it may work while they are still small.
Flat organizational structures are nothing new, many big companies practice this to a certain extent. For instance many IT consulting companies have armies of workers without the typical boss, but you still have executives/managers to actually run the companies.
Some companies will promote flat organizational structures but really often it is just a euphemism for lack of career advancement opportunities. So instead of employees aspiring to move up the ladder they are encouraged to move laterally (try different roles).
SEMCO, to me, is the best example of this. While they haven't fired all of their managers, they are a very large company doing self-management in a whole bunch of different verticals.
Github is at 230 people now. They use open allocation for devs and designers. Looking at the new hires section[1] on their blog, they also hire support personnel for teams. "technical writer, focusing on documentation for Github Enterprise."
