Technically, the announcement doesn't change anything on Twitch's end: streams that break third-party terms of service agreements (such as pirated software or showing a game running on an unauthorized, private server) have always been prohibited. Even so, the statement serves as a reminder to broadcasters: if Valve wouldn't be okay with your Stream, Twitch probably isn't either. Added to the fact that the owners of CS:GO Lotto have been added to an ongoing gambling lawsuit against Valve, skin-betting doesn't seem long for this world.