It will make things more difficult depending on the type of Brexit we have, if it's a hard Brexit I'll probably have to apply for a European Passport or even apply for Spanish citizenship.
I do know what will happen, the economies of the Costas will crash so it's not in Spains best interests to force expat residents to leave.
The whole thing is just a big mess, I know it's selfish of me for not wanting Brexit but anyone who travels to Europe from Britain will be affected. We have had free movement for years now and that is going to end.
Sorry this is getting way off topic so I'll leave it there.