With each halving, the period until a new Bitcoin is created doubles. It will become increasingly difficult, incredibly difficult for anyone to obtain fresh Bitcoin as time progresses.
Maybe your statement here needs more clarifications, bitcoin is at its best and nothing will depreciate it value, rather this will increases over time, maybe you will need to explain what you mean by the difficulty in obtaining a fresh bitcoin over time.
Horrible things like man made devastating wars will hardly be feasible and affordable anymore, because Bitcoin is simply too rare to be able and willing to wage war with it.
If the world economy can have no impact on bitcoin, what other measn or source can devastate bitcoin anymore? Obviously nothing, don't even start with the suggestions of things that are not.