cAdvisor is becoming an implementation detail of Kubernetes, and may even be removed entirely in the future (or pushed down into the CRI layer). The Kubelet's stats API has been available for a long time as the prefered way of gathering stats, and there are a number of solutions (e.g. influxdb+grafana) for cluster-level monitoring.

As such, we should begin the process of deprecating and removing the cAdvisor API surface. As a first step, I propose that we default the cAdvisor port to 0 (disabled), starting with Kubernetes 1.10, and add a deprecation warning to the flag.
EDIT: We should add the deprecation warning in 1.10 along with a release note, but not change the default. The notes should warn that the default will change in 1.11. We disable the flag by default in 1.11, and remove it entirely in 1.12 or 1.13.

If you currently depend on the UI or the API, speak up! Going forward, the recommended way of taking advantage of those features will be to run cAdvisor as a DaemonSet.

/cc @kubernetes/sig-node-proposals @philips @dashpole