Just think about it- City Defense wouldn't even have to be limited to the Last City on Earth. If we are liberating the galaxy, humans would have to start rebuilding cities on other planets, like Freehold on Mars and whatnot. We could accept missions to assist and guard those people as they rebuild and venture out on a mission to get artifacts or scientific gadgets and conduits to power the city. Then once the city is working again, more people come and make a living on those planets. There will be a constant need to protect each city as we expand into the stars, and depending on which one needs it the most it could have a severity rating, and more Guardian forces could gather to a certain city and risk possibly losing one or another. That's what a war feels like. That's the kind of war I feel the Guardians should be waging against the Darkness. Right now it feels like I'm just expecting to see the same Fallen and Vex spawn whenever I start a Strike and that we're on a Pokemon hunt for Exotic weapons- which the latter is pretty okay in my book. It's not just about Guardians becoming legend with cool weapons and gear, it's about the bigger picture, the resettlement of human race among the solar system.