Actually, in the near-term, the raise of minimum wage will lose or demotivate the better/skilled/more productive/higher paid employees.

Employees who are already making $15 or more will likely not get the same increase as the lower paid staff.

This will have a knock-on affect as it will create resentment towards the people who did  not necessarily contribute as much to the company’s success., but got a big increase in pay. This may also make the more productive employee's feel that their value to the company had been diminished.