Or other countries may also end up exiting the EU
How? It was political suicide for Cameron to hold that referendum. Why would any other government want to follow his example? I am not aware of any similar state of affairs in other governments regarding the EU as the one in Cameron's cabinet and hinterland.
I agree, that those currently in power, may decide to
not do it. But on the other hand, later there will be fresh general elections (in coming years).
So let's say the time has come for a new general election, in a different EU country.
For arguments sake the current main party there usually gets 55% of the votes, and the opposition 45%.
If the main party declares giving
no referendum, if they win the elections.
Then the weaker (45%), opposition, may offer a referendum vote on leaving the EU, if they think they will get more votes (than they lose), by offering it.
If they then win the election, their referendum, may have the same result as ours.