In your quote, the meaning of provide for is to act to prepare for something (Wiktionary, verb sense 2).
We may rephrase the quotation this way:
It turns out that there are contractual answers as well: creditors can prepare for these possibilities in advance, not between themselves but by taking security interests in your assets—in other words, a right to take back your property directly if you run out of money.
Let's look at an example sentence:
The architect provided for the possibility of storms by strengthening the abutments.
If you substitute provide in the place of provide for:
The architect provided the possibility of storms by strengthening the abutments.
the resulting sentence is absurd: stronger abutments are somehow supposed to invoke storms.