Complex sentence: Concerns grew in Vienna that Metternich's policy was too expensive, prompting Metternich to respond that Naples and Piedmont would pay for stability; nonetheless, it was clear that even he was worried for the future of Italy.
Split into simpler sentences: Concerns grew in Vienna that Metternich's policy was too expensive. He responded that Naples and Piedmont would pay for stability; nonetheless, he, too, was clearly worried for the future of Italy.