Allow streamers to form groups/networks, where sub badges are shared
I think it would be a wonderful community building idea, that benefits Twitch, streamers and subscribers equally. So, a streamer could combine with other streamers to form a small network of similar streamers (either friends, people they stream with often, etc.) in which all parties must consent to joining. This network could have a name, and maybe a widget on members' channel pages. In any network members' chats, all subscribers to any of the channels in the network will have all of their subscriber badges from the network (and only the network!) in front of their names.
I realize this is a lot of implementation for what really is a small feature, but eventually, the networks could develop into something greater; there's definitely potential in that idea alone.