Let's imagine for a moment that, for some bizarre reason, we have another referendum and the result is that we vote to stay in the EU.

If, at some point, a noisy minority gets fed up of the EU then do we have another referendum?  And if we don't like the result of that then another?

This is why Cameron said at the outset that this would not be a Neverendum - we have a vote then stick with it.  If you open the door to another then there's no justification in ever accepting the result of any future vote.

The EU as we know it won't exist in 10 years anyway.  The plan is that it will never stay still, but will gradually take over all aspects of government for all the countries involved.  It will either completely fall apart or will congeal into one country of Germany plus its followers.  So staying in but staying as we are was never an option - it's "ever closer union" or leave.