I think it will always be profitable, there are plenty of anti-ASIC coins.
As noted above if any coin becomes profitable with GPUs it is usually destroyed in a few months by massive farms moving in who sell every day, mutlicoin pools who autodump the coin, and eventually an ASIC invasion if the price remains high enough.
Pretty much all GPU miners have switch to multipools since no coin stays profitable for more than a few days (unless you have free electricity).