Okay, this is probably the the millionth time this question has been asked, but a search on this site for "Xbox live gold" yields little results. I'm hoping someone here has a better answer than "it's an online game, of course," seeing as theoretically, you could be locked out from forming fire teams or entering the crucible and still have a singe-player experience. At least that's what I gathered from the beta. However I was on gold at the time, so I couldn't be sure. I imagine this could also apply to PS4 with PS+ as well, but I am willing to bet Sony is more generous than Microsoft on this front.