So you unsubscribed. It happens. Much as we'd like to think otherwise, no MMO entertains us forever, and whether it's a patch that changed a lot of fundamentals or just a general growing dissatisfaction with the game is largely irrelevant. What matters is that you stop and let the game drift out of your consciousness for a while, until you really barely remember your favorite times in the game. That is until something catches your eye and gets you reading about all the things that have changed; until you find yourself drawing out your credit card and eagerly re-subscribing.
Just like no MMO keeps us forever, many games won't lose us forever, even if we take a break. The question is: what would spur you to start playing an old favorite again? A new expansion? Promises that the biggest problems you'd found had been fixed? A change in management? Or is it just a case where time heals all wounds and absence makes the heart grow fonder?