The end game here may be the EU deposing Cameron like they did Berlesconi in Italy.
I wish they would try, such a naked usurpation of national sovereignty might be acceptable in intrinsically pro-European countries like Italy and Greece, but Britain has always been Eurosceptically inclined and it would be the short, sharp shock the British people needed to wake them up to the danger of the EU. Up until now the British Frog has been put into a cold EU pot and boiled slowly...