Looks good to me.
Before removing the package from the robot_model source repo, it may be worth checking downstream packages to make sure nobody relies on the previous URI like it happened when we started moving robot model packages

@mikaelarguedas good idea. Looks like this is in the clear. I checked two levels down using the ros wiki Used by. All were on github so I searched for joint_state_publisher and robot_model. Nothing looking like a URL came up.

While Jade has just been EOLed you might want to make an effort to maintain the ability to build it from source in case users still want to do so.

@sloretz @clalancette I just noticed something fishy with EOL distros:
All distros before indigo are fine because they had their own branchs that stayed unmodified and still have all the packages in them.
Now that Jade became EOL it's a bit trickier because it uses the indigo-devel branch like indigo but that branch doesn't have the packages anymore so people cannot build them from source anymore.
Speaking with @tfoote the best way to go would be to create a tag jade-devel on the robot-model repo with the state of the repo before Jade became EOL and update the Jade disctibution file to point to that new tag rather than the indigo-devel branch

@mikaelarguedas PR #15927 updates the jade distribution.yaml to use the tag jade-devel. May I ask you to check if I missed anything in it?