EU doesn't have to "punish" them, they'll just be treated like everyone else outside of EU.
No single market access for UK after Brexit, Wolfgang Schäuble says
http://www.theguardian.com/politics/...-schauble-says
France warns Brexit would be irreversible, single market access at stake
"If the choice is to leave the EU ... that would be irreversible," Hollande said. "No is no, there is no middle ground and we'll have to draw all the consequences."
http://uk.reuters.com/article/uk-bri...-idUKKCN0Z81FT