According to the abstract of the following VMworld 2009 session, VMware will discontinue the classic Service Console-based ESX in the near future.
Session ID: TA4060
Title : The Path to COS-less ESX: Migrating Server Operations from ESX to ESXi
VMware ESXi is the next generation hypervisor architecture from VMware, offering improved reliability, security, and a simplified operational model. Due to the superior nature of ESXi, VMware will discontinue the classic Service Console-based ESX in the near future. If you are a long-time user of ESX and have developed your management procedures around the Service Console, then come to this session to learn how to migrate to a new, improved operational model. We will show how to adapt your process for all aspects of management, including: hardware monitoring, backup, systems management, user management, logging, troubleshooting, and more. You should be able to leave this session armed with the tools necessary to be prepared for the transition to ESXi.
Update : Changes to the ESX Service Console for ESX 4.0
This technical paper discusses incompatibilities between the ESX 3.5 service console and the ESX 4.0 service console. Included are suggestions of what you might do to upgrade your existing environments that depend on the ESX service console. This document also discusses how you might bridge the gap to support ESXi, which does not include a service console. And finally, if you are currently writing applications that run in the ESX service console, this document suggests some possible options you have for transitioning away from it.