This is the part of the GSW backcourt that doesn't really matter. Livingston and Clark are good players but they can be easily replaceable within that system especially being surrounded by Curry, Klay, Durant and Green.
I think you're underrating Livingston a bit. He's not irreplaceable, but it's also a stretch to say he's easily replaceable. He can very easily play on the court with Curry, letting Steph play off the ball a bit, without sacrificing size as he's 6'7" and long. When he's playing the point and Steph is on the bench, he can be a very hard player to guard with his ability to post up smaller PGs, especially with how Golden State can put shooters all around him. He's a pretty rare type of player, arguably unique, and is definitely creates mismatches when synergized with the rest of that roster. If he leaves, they'll find an alternative, but I highly doubt they get anyone who can replicate what he brings.
I like Clark as a player, but he's replaceable.