I think VM's with windows 2003 will continue running however they fall under Leacy support level category.
Legacy
The Legacy support level is between Supported and Deprecated. These guest operating systems are typically no longer supported by the original vendor. As a result, VMware's ability to support this guest operating system is reduced because VMware may not be able to collaborate with the OS vendor to provide the highest level of support.
VMware continues to provide support for OS agnostic features. These include:
- Virtual Machine lifecycle operations such as suspend, resume and power on/off/cycle.
- Snapshot, revert operations and management.
- Virtual Machine mobility operations such as vMotion and DRS.
Ref: VMware Knowledge Base