I heard years ago that fabric manufacturers classify yearly designs. I don't know if this is right but here goes:
A classification means it will only be manufacturered this one time. When it runs out it is gone.
B classification means they will manufacturer once more or see how the sales go.
C classification means manufacturers will make it for a few years in a row.
Classifications may be based on how well the sales go and the marketing goals.
This is a good question, I would like to hear more on this.
If you ask the quilt store (whoever does the fabric ordering) what the classification is and she/he should know - that will give you an idea of how available it will be for the long run.