Your theory is all well and good, I'm sure everyone appreciates you taking the time to delve so deeply into the lore of the game we all love. However, have you read the grimoire card for either xur or the nine, can't remember which it's called probably the nine. Anyway it's the one that says The nine are this.... The nine are that... The nine are this... Etc... Anyway they're all pretty cryptic descriptions that don't really lead one to believe they are worlds or planets... Also you may be giving bungie too much credit with your theory. Nothing lore wise we've encountered in this game would suggest that bungie even knows exactly what the 9 are or will turn out to be. For now they're just a mysterious faction that they'll decide what to do with at a later time, if ever even at all. But again kudos for wracking your brain and if nothing else creating an enjoyable read on a forum full of complaints, nerf calls, biased polls, stupid AMAs, and useless petitions lol.