1. These are easy to implement steps. The most important thing is: Reach out. Form a community. But this is hard. It is unlikely that Underground Gaming will suffer from a load of games plucking its channels; if this should happen, we'll need to create platforms. But as the whole thing only applies to idealists, the risk is low atm.
2. A form of community curation will be needed. But I don't intend to decide about such stuff alone. Also, it isn't needed by now.
3. Thats great! Sounds like you are a scene were Underground Gaming might (still?) be practiced. What I have in mind might be an opportunity to open to new, interested audiences and to exchange with developers from other scenes.
4. "This" is indeed a definition, combined with some practical steps that I have already taken. Note that definitions are important: If nobody would have defined "Taco" or "Punk" you couldn't eat nor make Tacos, neither could you play or listen to Punk music since you would miss the concept of both. This is - atm - the case for Underground Games for most people.