In consequence for those who are retired - The existing EU regulation which protects receipt of UK State pensions and benefits would cease to have effect. [The Winter Fuel Payment ( an OLD_AGE benefit under EU law) restriction is currently being challenged legally. Following a Brexit, it could not even be challenged!] - e.g. potential receipts of attendance allowance or any other social benefits from the UK would stop. The UK would have the power to modify the receipt of State pensions in Europe and even freeze them - i.e stop annual increments. Clause 20 of The Pension Act 2014 specifically allows for this (annual rises can be stopped for pensioners resident abroad).
States have the power to impose any law of their own on 'foreigners' i.e in this case of Brexit, British Citizens, without constraint from the EU - what laws, for example? There was a time (pre EU) when France taxed capital being brought into the country. The current challenge brought about by a Dutchman ( M. de Ruyter) which has challenged the imposition of CSG etc (social taxes) might not apply to the non-EU citizens. France etc. could impose any law it wished on non-EU citizen held bank accounts.
Conversely, there was a time when one could take out only a small sum of money from the UK, the amount was entered in the pages of the passport (M.Thatcher changed that rule). One can scorn such suggestions, but there would be no protection from the EU regulations, which would not apply.
You could not vote for an MEP. The existing EU law which entitles you to vote for an English speaking MEP is prevented for many of us because we have not a VOTE under UK law. [Again change is very necessary but it will never happen if the UK leaves.]
There would be nothing to prevent the imposition of French duty on imported goods from the UK.
Again the UK financial institutions are not honouring the EU regs on freedom of movement of capital and services by not allowing one to open a UK onshore bank account or investing in certain accounts and saving opportunities - Again these activities, although not happening should happen but if Brexit comes, there is very little chance of it ever getting sorted. It is another instance of the the UK dragging its heels on EU matters.
The inheritance law changes which have come about under EU rulings, whereby nationals could have they inheritance following the rules of their Nation State. could be scrapped. The UK has shown itself not that keen on the changes.
One would need some form of residency card.
Freshly arrived citizens would need to prove they are financially solvent or they won't get a residency card.
It could be that in the case of a Brexit that as one would have been an established permanent resident for a number of years, then one might be accepted for such a reason to continue in the system of the Resident State without the financial support from the UK. That would be expensive for the Resident State Such a State may seek different ways of getting some form of financial compensatory support - who can say?
British Students can at present get support to study in EU universities [The Erasmus Scheme]. That would cease.
Then one asks, what be the effect on the many tens of thousands of French citizens and others living in London and neighbourhood? That must be worrying them.
Lastly one asks what nuance of change of attitudes between our French (or other) neighbours and ourselves could appear? - Who knows - Think of our children in French schools, or employers of British Citizens, or the fonctionnaires (civil servants).
The EU surely needs to change but it is up to us to help the EU evolve. It won't be possible if Brexit comes about.
2....I am asked -- Do I see any advantages for the residents in the UK?
A stability in the population possibly? Even that is far from sure. There would be a hope that pressure on housing, schools, the NHS might ease.
But when we see pictures of Romanian 'immigrants' working in hop fields or pulling leeks in Lincolnshire - how many are truly permanent immigrants?
Looking at the French in London - French schools exist there; they are young and not so likely to have great demands on the NHS - except perhaps the maternity services. These are slightly cynical remarks but the demography of the migrant movements are different between the nationalities.
It is a most dreadfully complicated situation. I suspect that for many people, possibly with little understanding. immigration in Britain is confusing - the Pakistani/Indian influx is confused with European Romanian influx and the refugee crisis and the EU gets blame where it is not guilty. Much of the immigration is the consequences of actions by the UK Governments. Greater control of about 50% of the migrants is possible because they are not Europeans.
3. Some claim that under the the terms of the Vienna Convention on International Treaties between States concerning 'Acquired Rights' that all European expats would be protected. BUT-- France has not signed to that treaty, and neither it seems has the EU. The EU is not a State but a co-ordination structure between States of the Union.
Here are points of view from two lawyers who have been informally consulted.
If the 69,000 retired brits in France (about 450,000 reside in other EU States) returned it would have a major effect on the UK economy - you can imagine the difficult situation both for the returnees and certain public services.
The concepts of 'controlling our borders' or 'making our own laws' is to some degree misleading. The UK makes 83% of its own laws entirely concerned with governance of the UK. The EU Commission makes regulations which concern the co-ordinated economy and social life of a developing Europe not detailed laws on the internal management of the UK or any other State.
Democracy will have to spread much more widely through the EU migrant and indigenous populations. There are millions who have migrated around the EU, all EU citizens. Few of them and above all the British citizens are adequately represented by any government.
The Drawbridge Effect --- The Future for others
As for future generations of British Citizens wishing to work or live in other EU States, the drawbridge of a Brexit may have been drawn up and they will not be able to avail themselves of the advantages of which some of us had been able to enjoy. Pensioners would be impeded for financial reasons from retiring to live in EU States. Younger citizens would be impeded in seeking work, and even more so in establishing new enterprises or studying in such States.
Two years of Grace?
There would be two years after a Brexit were announced in which re-organisation is achieved. That suggests that nothing much would occur in that period.