Hi and welcome to the board. Not all fusibles are created equal. Some hold much better than others. Additionally some hardly hold at all if you didn't prewash your fabrics. For example, Misty Fuse does not play nicely with factory sizing so won't stay down permanently unless you stitch it down if you did not prewash your fabrics to remove the factory sizing.
Another factor to take into consideration; is your project a functional quilt, meant to be used as bedding or napping under and wrapping up in or is your project a wall hanging that won't get a lot of wear and tear and washing? Another question I have is when you wrote: "I plan to have it machine quilted with a close pattern.", does this mean you plan on having an all over pattern, also known as an edge to edge (E2E) done rather than custom quilting?
I would recommend that if this is a functional quilt to be quilted with an E2E, you secure your raw edges. The blanket stitch you mention doing may not keep your fabric from fraying. It is hard to say because there are so many variables involved.
I have quilted a few raw edge applique done with fusible where the maker did not secure the edges. These jobs were custom and they were wall hangings. I made sure to quilt just inside the edge of all the applique to ensure it would stay put. It was already coming up as I was working on it. I strongly suspect if the pieces were ever washed there would be some fraying.
A good rule of thumb with fusible applique is: Satin stitch will secure the edges and stop all fraying, next best is a small zig zag stitch, last is blanket stitch where some fraying is possible but not definite and finally a straight stitch just inside the applique will secure it but will not keep from fraying.