Bonuccis chances of ever becoming 1st choice captain will depend greatly on how long Marchisio will last. age difference between the two is 8-9 months, and we know Marchisio will be 1st choice captain after Buffon (and maybe after Chiellini) retires. Bonucci will at best be vice captain unless Marchisio leaves earlier than him, gets benched by someone better earlier than him or gets a terrible injury. it should go like this,
Buffon > Marchisio > Pogba but there is a chance Chiellini and Bonucci might be captains at some point