Nationalist movements are gathering momentum in other countries like
France, Italy, The Netherlands and Denmark as talk of referendums amps up.
Not everyone wants to be part of a socialist collective that smears borders and destroys the unique identities of member nations through a massive and smothering bureaucracy; Britain is not Bulgaria and shouldn't be forced to absorb any workers by virtue of some edict coming out of Brussels. To be honest, the EU reminds me in many ways of the USSR...
If restoring autonomy and sovereignty means borders and customs etc, so be it. Besides, it works both ways, right? The UK will have as much (if not more) ability to control the flow of goods and people into its realm. As well, the UK has 64 million people and is the 2nd largest economy in the EU; this is a lucrative market that can't be ignored by other nations in Europe out of spite or bitterness. It would be mutually destructive to impose punitive tariffs and the like.
The referendum is not binding. Parliament could ignore the results of the referendum and Cameron has apparently left the invocation of Article 50 to his successor. We'll see what happens over the next few months.