I adore Doncic (see who opened the thread lol) but there is no way he can stay in front of NBA PGs. He is about 6-8 and not exceptionally agile.
But the thing is Doncic is so versatile in offense, he can fit in many situations in different teams, and he is not a liability in defense - especially if he keeps filling out his frame like he did in past two years.
About floor/ceiling, I see his floor slightly higher than Hedo. His ceiling... I don't know, he is maybe the greatest European prospect since Gasol. For example Rubio was extremely hyped as early as 14 years old, but he had an obvious flaw in his game (shooting). Doncic has no flaw in his game, other than mediocre/average agility (not athleticism).