Now that most of us are finished grinning, I can say that I have taken advantage of the specials several times and the resulting subscription has always been additive. That is, the twelve months have been added on to my current subscription. For example, my membership currently runs until December 2016. I would assume that sub renewals would continue to work that way.

Speaking for no one but myself, I wonder about the return of the $99 special (which I truly love :D ). Around New Years, I think, GT announced prices were soon to rise but I don't recall seeing any new pricing or implementation dates since then. Haven't seen any specials since then either.