Just because of how young he is. Barring serious career-ending injuries, Jon Jones could be fighting long after DC retires. To put this into perspective, if Vitor Belfort beats Chris Weidman and goes on to dominate the MW division for a few years, do you really think people are going to be bringing up the fact that he lost to Tito Ortiz 15 years ago as a reason for why he's not a great fighter? No. People don't even bring that up now. So yes, Daniel Cormier could beat Jon Jones (and I hope he does), but I don't think there's anything DC can do to take GOAT status away from a fighter as young as Jon Jones when it's all said and done.