I believe the story in which Ben Reilly comes back and interacts with Spider-Man should be written by someone intimately familiar with Brand New Day, so it wouldn't seem like a story which exists solely to bring back Ben Reilly (while possibly being at odds with events in Amazing Spider-Man). If that's a hit, a Ben Reilly monthly becomes a lot more likely, and it can be written by someone else.
There are still a few reasons to do a Scarlet Spider book. It'll appeal to some of the Spider-Man fans who left after OMD, and a few of those who remain on the fence with the current Amazing Spider-Man, those most likely to drop the book after a stretch of weak issues, or for reasons that seem trivial. JM Dematteis would probably agree to write it. It gives an excuse to reference the clone saga, some of which was decent. While there are disadvantages to guiding readers to the Clone Saga trade paperbacks, it would probably result in some new sales.