I would like to know if CNI plugin is enough stable to be used and if there is any plan to be supported for Istio 1.0.x. What I have understand from the Status of Istio 1.1 thread that it will experimental in Istio 1.1.
Sorry for the late reply. I was not monitoring discuss.istio.io much prior to 1.1 release.
As you mention the Istio CNI is indeed officially experimental for 1.1. That being said, the primary integration is with the installation and the setup of the istio-sidecar-injector configmap. So, the Istio CNI 0.1.0 should be usable with Istio 1.0.x as long as the istio-sidecar-injector configmap is modified to remove the istio-init from initContainers section of the template.
See the following discussion for more explanation on modifying the istio-sidecar-injector configmap: