It appears to be that at this moment the only thing you can count on with reasonable
certainty is that you'll be able to enter the EU for up to 90 days. Everything else at this
stage is speculation, best you can do is make provision for substituting alternative
provision for the privileges that will no longer exist, such as the EHIC, and as JohnH
lists.
Me, I'll just go for the usual +90days in mind and hope for a temporary reprieve/amnesty
on the no more than 90 day stipulation,
Trust me! they'll give those of us there at the time 14 days notice to remove ourselves forthwith.
But I won't be that surprised to get a fine!
After all we are supposed to register after 90 days even now, but this was mostly
observed in the breach ! So many of us aren't abiding by the rules even now.