Honestly speaking, Rondo will not gonna receive much game time on Lakers tho.
Because he has a conflict of position with Lebron, when Lebron played with the Cavaliers in his last season, he was very effective as point guard and that's why he brought that style of play in this team now, maybe if he has a star player PG he might not take the position like the time when he was still playing with Kyrie Irving.
I dont think another superstar PG would complement Lebron's style of playing today. As you said, he have effectively fill that position very well, because he is an offensive threat. When Lebron is carrying the ball he could draw multiple defenders leaving his teammates wide open, plus he has good court vision and passing ability too. Even with Iso, he would kill a single defender.
What Im seeing with Rondo rn is a good back PG. Maybe he could start at the starting line up too, but I doubt It. When Kuzma comes back, he'll probably start at the first 5 along side Green, AD, and McGee. So, whos gonna play at the PG position? Obviously its gonna be Lebron.