I don’t think people in that situation have much to worry about either, David. In the event of no deal, they’d lose the S1 presently given to them as dependants of a UK worker (it’s not even clear whether they’d keep that with the current deal as it seems to be only pensioner’s S1s that are mentioned) but as long as they can prove that they have sufficient resources they’d be able to join PUMa - though I’m not sure how their financial contribution would be worked out. On the spouse’s whole income or based on a maintenance amount paid to them?
The people who are really in an ambiguous position and need to sort it out are those who aren’t ‘lawfully resident’ here according to EU rules. People who haven’t really registered as being here, joined the healthcare system or made a tax return. Also people who have done all that but are inactive and don’t realise they haven’t met the EU minimum income requirements so that stops them from being considered legally resident.
France doesn’t register us here or check our status until we do things like apply to join PUMa as an inactive (without an S1) or claim child benefit or a means tested benefit. So someone with an S1 and no dependant children could live here at the moment with no problems but if we all have to have residence cards in future, the lawful residence criteria will be checked. If you aren’t working and can’t prove you’ve had 5 years at the right income level and registered for healthcare then you won’t get a permanent residence card. If your current income is ok then you should get the temporary one but that means maintaining that income for five years, before getting the permanent card.
One thing that’s surprised me since the referendum result is the amount of people that aren’t in a ‘regular and stable’ position as per the EU residence criteria. Not that this is brexit’s fault as people should check the rules before moving to another country, but just as the UK hasn’t followed the rules in the past (and is now trying to enforce them retrospectively and using the permanant residence card as a means of doing so), France, though not as lax as the UK in that they don’t usually allow people to become a burden upon the state if they’re not active, have let a lot of us live here whilst not correctly ‘exercising treaty rights’.
A vulnerable group are pensioners, who may not have realised when they came here, perhaps a few years (but not 5) before state pension age, that the income requirements increase after age 65.
It’s not scaremongering to advise people to check their situation against the current rules and make sure they are lawfully resident - and if not, do their best to do something about it before the potential exit day (I’m still not convinced it’s going to happen, personally).