He would definitely be weaker but that is because he grew basing his fighting style/techniques around Sharingan. So removing this now, would decrease his power for sure. But if he never had Sharingan from the start, i'm sure he would have been vastly superior to base Kakashi we see currently.
He was already a jounin at 9, learned rasengan when he was around 8 and created A(or S-rank) technique like Raikiri. After gaining the Sharingan that helps to copy technique, as stated he based his fighting style around it, but with his talent i'm certain he would have improved but differently, by maybe creating other techniques. His use of clones remains unique for example, maybe he would have developed around it. Without Sharingan he has much more chakra after all, since Sharingan would not be there to drain it