So this happened. VMware has pulled the ESX Classic binaries from being available as a direct download:
While they do provide a download link for ESX classic, it sends a pretty clear message… If you haven’t made migration plans, NOW is the time to do so.
Thankfully, they’ve not left folks completely out to dry and have provided some basic ESXi migration guidance here.
Additionally, I’d suggest as a first step, installing ESXi as a VM inside VMware Fusion or Workstation to become familiar with it before migrating your production hosts. Like using Fusion/Workstation for other test/dev workloads, this should be no different. Test your tools, agents, processes, etc against the VM image before blowing away a production host.