The short answer is, yes.
We are already at work on a version of our platform that will support VMware’s next generation hypervisor, and expect to make a formal announcement on timing in the near future. However, while ESXi itself is “freely downloadable,” the ability to remotely manage an ESXi host still requires the purchase of at least a “Foundation” license from VMware. Without at least a “Foundation” license, the ESXi host only allows read access to its APIs and therefore cannot be remotely managed by Surgient, or any other management tool including VMware’s own Virtual Center.