Say that Hasdrubal is given a bit of luck and succeeds in destroying the two Roman armies sent after him led by Marcus Livius Salinator and Gaius Claudius Nero at Metarus. He succeeds in meeting his brother in southern Italy and bolstered by fresh reinforcements and a promise of support from his Italian allies, Hannibal decides that now's the time to besiege Rome and succeeds in capturing the walls. The Carthaginians demand the Romans to surrender but being stubborn, they refuse and in the end, all Romans are either dead or made slaves to be sold in the markets of Carthage. There are Roman forces in Hispania led by Scipio Africanus who has successfully seized Carthage's holdings in the Iberian peninsula, troops presumably trolling Hannibal's Macedonian allies in Greece and Marcus Valerius Laevinus mucking shit up with his fleet in North Africa. With the Eternal City gone, what would the Romans outside of Italy do once they hear of Rome's destruction? Fight on or flee? And if they decide to flee, where would they go?