Smalling is 50/50 I reckon. He could easily carry on being as he is now for the rest of his career, or he could have some sort of epiphany and become a monster of centreback. Gut instinct is he's not smart enough or interested enough in becoming a top defender and will remain an average PL centre back.
Watched that Felipe Anderson video you posted somewhere above, Klaus (and a few more since), and he does look frighteningly quick and powerful. Maybe not the best touch and technical ability though? Not an overly good passer or very aware of his team mates either? Or have I got the wrong impression