Well, it depends on what you understand by going "full Nazi".
Personally, I don't see them literally doing the same things the Nazis did, i.e. arresting the opposition, stopping the elections from happening etc. What I can see them doing is making the country authoritarian: limiting the oppositions power, using the state media for propaganda, curtailing the rights of the minorities etc.
What will I do, if that happens? Most probably, I'd try to wait them out and hope that the nations kicks them out of the office during the next elections. But, of course, that might not come, if the PiS propaganda turns out to be successful... :(