The only game I can genuinely see taking a significant amount of destinys playerbase is fallout 4 BUT FO4 is probably at least 6 months away(at the very earliest id say christmas 2015) and if its anything like oblivion/skyrim/fo3/nv it wont have pvp or any form of co op If Treyarch went back to WW2(or around current time), had an amazing zombies mode with infinite replayability, and FO4 released around the same time then I would say yeah that would probably take a big chunk of destinys players At this point I think most people who are still here are in it for the long haul