As BillJ points out the key is the conditional "if". Since the event hasn't happened yet, it must point to a potential future outcome. Other examples:
If I don't get that dress, there's no way I'm going to the party.
If he doesn't close that big sale, our company is bankrupt.
In both cases either the event hasn't happened, or I don't yet know the outcome of the event -- but nevertheless when it does happen (or I do find out) there will be consequences.
This construction implies the strong possibility that the desired outcome will not happen, but it may not be the fault of the person responsible. Compare these:
If Ron doesn't pick up some milk, I can't make your birthday cake.
if Ron won't pick up some milk, I can't make your birthday cake.
The first implies that Ron is expected to buy milk, but for any number of reasons, he might not. The second implies he might not do it because he doesn't want to do it.
Note also that the nuance can vary with context. For example, "If I don't get that dress" implies variously that I might not be able to afford the dress, or that it won't be available in time, or that someone else might buy it before me.
Alternate phrasing for these examples:
Either I get that dress, or I'm not going to the party.
Either he closes that big sale or our company is bankrupt.
Either Ron picks up some milk, or I can't make your birthday cake.