"The sky's the limit," Wade told ESPNChicago.com on Wednesday after a promotional appearance for his new book, "A Father First." "He's been very good. He has three MVPs. I don't know statistically how much more he can do, but I think just his dominance of a game and starting to really understand everything about the game now. It's starting to all come together. That's the scary part."
Wade can see James' confidence building as the years pass. James became the first player since Michael Jordan in 1992 to win a regular-season MVP award, an NBA Finals MVP award, an NBA championship and an Olympic gold medal in the same year.
"It's here. This is the time," Wade said of James. "(He's) 27, you won a championship, you had success, it's not going to go anywhere. You can see him now taking that next step to that next elite level. I thought he proved it this whole season. I thought he was dominant from Game 1 all the way until the end, and he proved that that's not easy to do and there's not many that have ever done it."
Wade also said he has no problem with James continuing to work out with Oklahoma City Thunder star Kevin Durant during the offseason. Wade believes James is just doing his part to grow the league as it pertains to training with Durant.
James' Heat beat Durant's Thunder in five games in the NBA Finals last season.
"They worked out last summer; they've got a great relationship," Wade said. "It's just two of the best players taking things from each other, in a sense, and seeing the other person's work ethic so they push each other to be good, and I think on the other end it's LeBron being kind of the veteran in the sense that KD is the future of this game as well.
"He's not afraid to say, 'Listen, let's go work out in the gym together. Let's make each other better.' It's a good thing."