Set up new TV with Roku Platform Built In

Currently have a Sony TV and stream with a Roku plug in 4k streaming device.  Looking at several new TV's with Roku built in the television set. With the new set that comes with Roku built into the set how do I set in up with the old Xfinity X1 cable box.

My first thought is switch to the TV  input where the Cable Box is plugged into the TV by HDMI cable and go through the menu like I did when I first got the X1 Box. Then I guess when I want to stream I switch to the TV input where the Roku is located.

Thanks for any help to get all this set up without to much trouble.