Why can you not cast the xfinity tv app with a chromecast anymore?
The current licenses do not allow it (per the producers/providers of content). You can use a desk/lap top and link by hdmi to the TV.
Current content license agreements prevent Comcast from enabling this feature on there applications. In order for the feature to work, Comcast must allow the applications to take advantage of the Chromecast features, but many things may prevent Comcast from doing so such as the content provideers and that it may allow people to watch content without having to subscribe the to set-top box rental fees. There are many pros/cons to having this feature activated or not. I hope this information was helpful.