There are already plenty of people that consider him the GOAT. He isn't, yet...
If the Cavs can pull this off and get at least one more before he decides to retire I'll agree he will be the GOAT. He doesn't have to get more rings than Kobe or Jordan but he's gonna need to win 2 in Cleveland to get that honor.
That being said. It's hard to argue him not being the best. I mean he has been in the finals the 5 years now. If he play 7 more years my money he's in the final at least 5 more times.