In order to properly utilize the capacity you have in your data center which is highly underutilized, you have to embrace private cloud computing or in general Software defined Computing. Here we will be able to pool the resources namely Servers, Storage, Network and firewall devices. So you will be having a complete picture of what resources you have and capacity utilization integrated with proper monitoring. You will be able to take call on when to purchase the new capacity and where you can resize to get a cloud grade management of your in house infrastructure. Here it will be easy for you to embrace hybrid cloud architecture with subscriptions to AWS, Azure etc.