It would weaken us though particularly if we lose Kane, he will be replaced by an inferior striker because everyone is compared to him. If we got rid of Son for a more traditional winger as you suggested they may provide more service but to a striker who is definitely going to miss more, see the problem?
Yes his build up play is his weakness which is why you play to his strengths, he is pretty comparable to Salah who is also a fairly one dimensional player with high scoring output that offers little else ... doesn't mean he is shit, just that he is very good at a few things. Most players are like this.
Build up play must have an end product in the form of goals or assists which is where Son thrives, I don't mind having a winger being a main contributor, I would rather our central players take more responsibility for progressing the ball forward through the lines but they have been poor.