This is a highly subjective question, and the answer, IMO, must also be taken with a grain of salt; however, I suggest that the War on Terror will never be over.
The "War on Terror" generally refers to the military campaign launched by the Bush administration to effectively wipe out Al Qaeda and other militant groups of similar ideology in the wake of the September 11th attacks. While many of the designated targets were indeed disrupted and/ or destroyed, terror cells continue to bloom throughout the Middle East and other areas friendly to extremism, and there has been disturbing evidence suggesting that America's efforts to use military force to quell such organizations have actually bred a new generation of anti-American sentiment that results in new terror organizations forming, but in less detectable ways and almost impossible to engage military forces in.
Bush defined the campaign's ending as such: "(o)ur 'war on terror' begins with al-Qaeda, but it does not end there. It will not end until every terrorist group of global reach has been found, stopped and defeated."
Since we now seem to be breeding our own terrorists, it seems unlikely this is a winnable 'War'. In traditional war, this would at best be called a stalemate and at worse a complete loss; however, since this is a political/ social term and not a true "war" , declaring the War on Terror anything other than an indisputable victory would not be politically feasible.