Also remember, you may have customers that are attached to employees.
Sometimes employees may know how to get things done fast. This usually is more applicable to technology, such as knowing the system.
When I was in the corporate atmosphere, I worked at a store where the managers did not know how to work one of the exchange systems for products. Imagine if both of those employees left, it would have been a nightmare.
That is the only thing I would worry about when cleaning house.
An entrepreneur tends to bite off a little more than he can chew hoping he'll quickly learn how to chew it.