There’s now a blog/news post on Unreal Engine page for the topic here. You can also get the plugin from marketplace here
Good conversation on the subject. I would like to point out one thing about these hosting solutions and that is region based servers which means lesser latencies. For example GameLift provides good coverage on entire globe and I’m pretty sure Photon and others have similar solutions. Correct me if I’m wrong but I don’t think using Steam and GameLift cancel each other out. Granted it might be little more complex to get it working than using purely Steam and the player hosted servers.
Also worth mentioning is that when you use the player hosted servers there is more risk running into foul play. Players running custom servers and cheating are more of a issue when you don’t have full authority of the servers running the game. Then again it depends on the game how much of an issue that is…