A media company runs its core application on Amazon EC2 instances. A solutions architect has standardized the infrastructure on a specific EC2 instance family and has selected multiple instance sizes to match current workload demands. To reduce long-term expenses, the company wants to commit to a 3-year pricing model. However, the team anticipates possible changes to both instance families and instance sizes within the next 6 months due to changing traffic patterns and feature adoption. What is the most cost-effective solution that still allows flexibility to adjust the infrastructure?