Not much, its about giving GGG a final chance of absolute glory and also putting Canelo's legacy in perspective. Its actually a similar scenario to Marquez-Pacquiao 3. After the 2nd fight Pacquiao went on to blitz the higher divisions and many assumed that the difference would finally show in the third fight, however Marquez gave Pac hell just like ever...so this brought up questions as to how good Pac really was. Same thing here. If GGG gives Canelo hell in a third fight, then the idea of Canelo always getting better would be disproven. That would open up the doors to haters beginning to state Canelo's run at 168lb was indeed b/c of low competition and that an old GGG would have blitzed through Plant, Smith and Sanders just as easily. The only thing Canelo would gain from a third fight victory would be closure and knowing that he got the better of GGG in the long run. But legacy wise, the fight is a risk to Canelo.