VMware announced that the
C# client will not be availiable in all new vSphere releases.
The Web Client will come for everyone of you.
The Web Client will be based on HTML 5 (*yeah*)
Some days ago the update of the HTML5 Web Client was released (1.6.0).
https://labs.vmware.com/flings/vsphere-html5-web-client
Severall new features and Improvements are waiting for you to test.
Two ways to install are possible (fresh install/update)