VMware vCenter Heartbeat is not available anymore for purchase starting June 2. All support and maintenance for the removed versions will be unaffected and will continue on per VMware Life Cycle policy through the published support period until September 19, 2018.
VMware vCenter Server Heartbeat is a software product (OEM of Neverfail) that protects vCenter Server against outages–from application, operating system, hardware and network failures to external events–regardless of whether vCenter Server is deployed on a physical or virtual machine.
vCenter Server Heartbeat creates a clone of both the vCenter Server and the SQL server database used by vCenter, and then keeps both the primary and secondary vCenter Servers in sync through continuous asynchronous replication. Administrators can use vCenter Server Heartbeat in a virtual configuration, physical configuration or a hybrid model.
The reason for the end of life is that VMware believes current available protections like VMware HA, vMotion and Storage vMotion ensure availability of managed resources.
I *guess* a couple of reasons to stop selling vCenter Heartbeat could be:
1. most customers are using vCenter running in a virtual machine. They are happy with HA
2. sales of vCenter Heartbeat are reducing because of point 1
3. vCenter Heartbeat is a complex product
4. vCenter Heartbeat was a pretty expensive solution not many customer were interested in.
5. It might give VMware too many support headaches because of upgrade issues vSphere 5.0 -> 5.5 combined with SSO.
6. As of vCenter Server 5.5 in vSphere 5.5, VMware introduced support for using Microsoft SQL Cluster Service for use as a back end database. See this KB for instructions.
7. VMware is working on a new way to protect vCenter Server
More information in the VMware blog here. Answers to frequently asked questions are here.