I've basically just been waiting for it to happen for years. We already have so many languages that range from "javascript + some" to completely different languages that all compile down to JS, and it hasn't killed the community yet. Worrying about "where will a newcomer start?" is about as pointless as worrying about where a new programmer will start. I mean, I already have the choice of countless languages for the desktop, getting that exact same freedom on the web seems like a great idea!