What is the incentive for people running execution clients in proof of stake Ethereum?

If I understand correctly, in the coming proof of stake version of Ethereum, there would be the beacon chain, with blocks on it created by validators. These validators will get compensated for doing this.

There would also be another chain (execution chain) where clients like Geth will create blocks that contain transactions information and where smart contracts are executed. Previously operators of these clients get rewarded based on the proof of work consensus model. But with the move to PoS, and validators providing security (and getting rewarded for it) where does the incentive for folks running clients like Geth now come from?