The only thing Tatum really suffers from IMO is the expectations put on him. I remember after his rookie year listening to a podcast where one of the hosts asked the other two if they expected Tatum to be a "top five" player in his prime. Another host responded that he would be "surprised if he wasn't." That story simply reflects that fact that everybody expected Tatum to be really good, really soon. There were people asking last year at age 20.5 if he would be the best player on the team. The thing is, 21.5 year olds OCCASIONLLY HAVE A BAD GAME. Players that age who take on a significant scoring responsibility can often be inefficient, that doesn't mean we need to ask whether we should trade him after every bad game. I expect he will improve as the season goes on, and over the next couple years because most young players do.
I dont know exactly what Tatum will be. Maybe he's as good as Durant, maybe as good and Peirce, maybe a better Tobias Harris. It depends on exactly how much his skills improve. But given how good he s right now I wouldn't trade him for less than an elite under 25 guy (Giannis, Doncic, Towns).