According to Expectancy Theory, employee motivation will remain high when the P-to-O expectancy falls to zero.

Expectancy Theory

A theory in motivational psychology that describes the motivational force as a function of an individual's belief in the likelihood of achieving desired performance levels and the perceived rewards associated with those levels.

P-to-O Expectancy

The belief that putting in a certain amount of effort (Performance) will lead to a specific outcome (Outcome) in the context of expectancy theory.