Consider: the fact that the perfume will be used up is a part of what makes it precious to us. An unlimited supply leads to boredom; scarcity lends an edge. We value what is in limited supply.
I have truly found that most of my favorites do get discontinued-- so I have a spare bottle or two of the ones that are actually discontinued (and store them in the fridge.) But I don't buy spare bottles of current fragrances-- even were they to be discontinued, they would be available online and at discounters for a good while.
Consider also this: the perfumes will smell the best while fresh. Give yourself permission to enjoy them!
Also: if you do not use them at all, then effectively it is just as if you didn't have them. If you don't ever wear them, it is the same as if they were no longer available--right? Think about it.