What challenges will the company face if they shift their focus from "Customer First" to "Employee First"?

Decrease in profit, & it will hurt the image of the company in the long run.

The company has two types of customers one is internal customers i.e, (employees) and external customers i.e, (clients/customers/service takers.) If the focus has been changed then the profitability and goodwill of the organization will decrease and disturbed because customers come first.

depend on the situation , professional companies has to maintain the satisfaction of the internal customers (employees) and the external customers (the real customer) .

Company has to balance themselve between customer and employee.
For the growth of company both are very essential.
If anyone goes down the ultimate suffer is the company.

You cant rate customer First and Employee First as two end points if you are serious about business, To be built a long term profitable firm u need to make an environment of Employee First as long as Employee can keep the Customer Satisfied and happy

Customer dissatisfaction and as a consequence loss of profit and brand if employees do not serve appropriately