You're delusional if you don't think Dtube is immune to copyright. If push comes to shove Dtube can shadow ban videos if nothing else and if there is some technical reason they can't copyright holders will take over the site and make it so no one can see any of the videos. Sure, offending videos might be able to be accessed because it is decentralized but it would only be a matter of time before they'll start hunting down the people that are hosting the videos.

Beyond that I really think the only way a live streaming service can work is if it has a good donation system. Steem is nice and all but if they set up a system for other crypto currencies or maybe even found a way to incorporate paypal I think it would be a good competitor to Youtube and Twitch. Other live streaming services don't have a good donation system setup.