What would be the costs to an organization of losing top executives or high-potential employees as the economy improves?

During the recent economic downturn, as companies scrambled to cut costs wherever they could, many hoped they could count on their top talent to stick around in spite of the belt tightening- after all, they should be grateful to have a job. Some evidence suggests that this hope may have been misplaced.
Worse, the most valuable employees seem to be the ones who are least grateful for the chance to stay with their employers through hard times. According to a survey by the Corporate Executive Board, the percentage of senior executives "willing to go above and beyond what is expected" fell by more than half since before the financial crisis.
The same survey found that one-fourth of employees identified by their employers as having high potential were planning to quit their job within the year. Similarly, an annual survey of employees conducted by Watson Wyatt Worldwide and WorldatWork found that employees' commitment to their employers has fallen, with the largest drop registered among the highest performers. Part of the problem may be a false hope that companies can meet employees' desires inexpensively.
In a survey by Spherion Corporation, employers said workers' satisfaction depended most on a positive work environment and good relationships with supervisors. Employees, however, said they cared most about pay and benefits.