In the old days, if you dropped out, you went to Gitmo or in-country Vietnam, or some god forsaken place in the Aleutians. Gitmo was preferred.
Some went to the Oak Knoll Psychiatric Unit, more then you would think, but that is another story.
The bottom line is if you fail to meet your contractual agreement, you ass is at the mercy of the Navy.
If lucky, they will kick you of the service for failure to meet your commitment.