You'll have to wait another few weeks for the honeymoon phases of all the new releases to pass to see if destiny dies. Halo, then black ops, then fallout in consecutive weeks of course the active player base will change. After all destiny as of right now only has destiny 2 scheduled for next year, so if nothing comes out of course it'll die because their are loads of new games coming out. However you'll know if it truly died when destiny 2 releases.