I've unsubbed and resubbed several times. If you mean permanently, I do plan to resub for one last time after Dawntrail release just to get my character a full set of ilvl 660 tomestone gear and check out the graphical update. After that, I will unsub permanently and only play during free login campaign.

However, I have a separate free trial account that I plan to play after I retire my main account so I probably will never not play FFXIV until the devs decide to pull the plug.