How long a quilt will last depends on many factors of which fabric quality is only one.
How will it be used?
How frequently will it be washed?
How closely are you quilting?
Will it be in direct sunlight?
Is there chlorine in your local water supply?
How long is acceptable to you?
I do not make heirloom quilts. I make quilts to be used and abused. I would rather a quilt I make be in rags in 5 years, than sit on a shelf for 50. My quilts go to the beach, park, cover the seat of my car and sofa to protect the underlying upholstery from dirty pet feet.
My quilts will be washed in the machine and line dried in summer, but will go in the dryer in the winter.
The one place I am cautious is with binding. It often gets more wear and tear than the face or back of the quilt. I like bias binding and tend to use new (less than 10 years in stash) for that.