The current thought I hear most often is that once a brain is addicted, the brain never goes back to before it was addicted. It is always at increased risk for addiction.
What do you mean by physically addicted? Do you mean having a higher tolerance or withdrawal symptoms?
I went 16 years without alcohol-- and as soon as I started drinking again, it was a huge problem immediately. But I have seen posts where people say it took up to a year for alcohol to become a big problem again. I am sure it is different for everyone.