What you’re describing is a temporary setback and loss of productivity for the company. Almost never is it make or break situation for the company. You can hire

What you’re describing is a temporary setback and loss of productivity for the company. Almost never is it make or break situation for the company. You can hire someone who doesn’t care and is not motivated as the person who left, but the net effect to the company is marginal. In the rare occasion that a single person is valuable enough that if they leave, the company would shut down, the person is well compensated.