I would say my biggest concern regarding Tatum's ability to become a high volume scorer is that he doesn't generate a lot of contact. He is going inside more, which is good, but he is still scores more with grace and agility than strength.
Top scorers tend to buttress their shot-creation prowess with 7-10 free throws attempts a game.
That's the major difference I see between Tatum and Paul Pierce. Paul was a master at getting to the line and did so frequently.
Paul was stronger and better at getting to the line, but even taking that out of the equation i felt that he was impossible to stop in one on one situations. When Tatum is in one on one situations, it's hit or miss it seems.
That may be true, but I would say the value of those 1 on 1 scoring possessions was overrated. Teams have figured out that it's generally not ideal to rely on isolations like that to get offense.
Tatum is just okay as an iso-scorer; he's excellent at finding his way through openings in the defense to get good shots inside or from range.
Tatum probably will never be the stutter-step herky-jerky get-to-my-spot midrange one-on-one scorer that Paul was. Of course, few players in the history of the game have been as good as Paul was at that style of play.
Tatum has the tools to be a 20-25 ppg scorer with very high level efficiency. To be able to do that, though, I think he would need to get to the line a lot more often. Perhaps that will come with time as he grows stronger and gains confidence drawing defenders out of position.