Yeah something like that would possibly work, but if your pc is going to be inside the cabinet then you want at least 1 intake and 1 exhaust and make sure the intake is cold air and not just the ambient air circulating. Think like a tumble dryer vent duct to either vent exhausted air outside, or to pull colder air from outside in.
Ideally though you shouldn't box your pc away as in addition to airflow through the the intake and exhaust pathways, convection cooling and simply being able to radiate heat into an unconfined space are pretty paramount.
Ideally though you shouldn't box your pc away as in addition to airflow through the the intake and exhaust pathways, convection cooling and simply being able to radiate heat into an unconfined space are pretty paramount.