I fear the EU will take them right back and set a precedent for leaving and rejoining without so much problems as figuring out new contracts and agreements.
I'd demand worse terms for every time they leave and then try to rejoin (aka the cut was 50% but now the contribution has to be at least 55%)
I dont think so. Its in the EU interest for them to come back in. It will show others that leaving is not a good idea. However, they wkbt want it to be easy as it might encourage others to leave. They will join in the same terms as new entrants.
They will have to join the euro and they wont get their previous favourabke rebate for agriculture.
Its still a good deal for both sides but Britain make a mistake, as most are aware.
All it takes is for one member country, no matter how tiny, to say "No" and it's no, and in some countries like Belgium even a single region (say, "mighty" Walonia) can block it.
For example, I expect that Spain will want Gibraltar back as a condition for a Yes on a UK Membership vote.
In regards of Gibraltar, the problem is it being a fiscal paradise. If one of the agreement was that Gibraltar has too have the same rules as the rest of the EU it could be enough for the Spanish government.
And if that meant enforcing the same for Ireland and Luxemburg, even better.
It's my impression that it's actually a lot more about national pride for Spain than about Gibraltar's fiscal paradise status, since Gibraltar as not part of a member country can just be treated the same as any other offshore fiscal paradise, such as the Bahamas, which includes it being added to black lists. In this day and age, it's not geographical proximity that matters when it comes to fiscal paradises.
This makes sense since Britain too doesn't really gain much from having possession of Gibraltar so holding on to it is mainly a question of national pride for the UK - it would be strange if Spain's motivations were wildly different.
PS: Also it's funny how during the Leave campaign a lot of the "reason" why the EU would give Britain quasi-membership rights (without the responsabilities) after leaving the EU were a lot like this, about how those other countries or interests inside those countries would do it because they stood to gain monetarilly from it in the short term. All that turned out to be mainly wishful thinking and a serious misreading of the motivations of the leaders and people in said other countries.
Just found it funny how there are still people around thinking other countries are mainly motivated by the short term gains in sovereignty affairs, even whilst Britain itself again and again keeps doing things motivated by national pride when it comes to such affairs - one would've expected that "they're a lot like us" would somehow been figured out by now.
A single region within a member country can veto an entire block's will, even if the rest of the country assents? That seems very broken as a voting system, to me.
Belgium has an unusual constitution that lets its regions have veto power over some of its decisions in the international stage and adding a member to the EU is actually a change to a major Treaty that Belgium is part of.
For most EU member countries, there is no such thing, though I believe some (Luxemburg, Malta?) are actually smaller than Walonia in terms of population.