It depends on whether they can hold it or end up in destructive fights with the Spanish.
Embatassingly, I don't know much about Austrian rule in South Italy, but the Borbone were rather successful in the xviii century, especially during minister Tanucci's tenure, as he did much to modernise the country.
It depends on how the Wittelsbach take to their new kingdom and how they manage the dualism between continental Italy and Sicily.