If Bitcoin were to hit some limit, I dunno what, just maybe there is a limit in the code which people might start writing threads about on bct, but anyway, if Bitcoin hit some limit and couldn't scale anymore, then the network effect is arrested. Bitcoin, just being software that can be copied does not have the privilege of gold which is a rare physical element. Some other version of Bitcoin, an existing alt perhaps, which can scale will build up its own network effect from all the users who can't use Bitcoin. If Bitcoin found some crazy limit where only 1% of 1% of the world's population could use it, then it would become obsolete. It would be a footnote in the history books written about the alt which eventually succeeded as the new electronic gold standard.