Calvin Reid has a PW piece about Comic-Con (here in San Diego), and about how it could be a model for what to do with the BEA/ABA. (here is the link) http://www.publishersweekly.com/article/CA6674286.html?nid=2789&source=link&rid=1494249144
Obviously the big difference between the two is that a traditional trade show like the BEA is B2B-oriented, while Comic-Con is a fan-driven show that brings Creators (writers/artists), publishers, studios, distributors, dealers, etc together in one big stew.
However, if book publishers are serious about digital marketing and developing strong vertical categories, then they need to seriously consider fan-friendly shows conceived around strong subject categories. Publishers could collect fan information (to market to them) and gather their feedback about upcoming books. Involving authors, specialty retailers, other publishers in the vertical, other media in the vertical (web, Video, magazines, etc), bloggers, reviewers,etc could give enough scale and attention to make it compelling.