It's just a comparison, they have a similar skill set and size. I suppose he could say "he reminds me of a thin zach randolph" or something like that? It's a comparison he'll always have. If he doesn't become great(lets say multiple all-star at least), it'll be "why couldn't he be as good as nowitzki?" and if he ever is great it'll be "he's become his own player, different from Nowitzki".