The guaranteed next step is to offer the volunteers a long term paid contract at the end of their term. This would probably be well above what they would be paid elsewhere (young men with no university degree, desperate enough to volunteer in the first place).
Run the scheme for a few years, and you will have a large number of, young, high-school-level educated people that are financially dependent on the army. Thus, a militarized society.
What could possibly go wrong?