Alternerd Reality is reporting that Mysterio is set to be joining Marvel Strike Force. According to datamined info, Mysterio is set to be a City Controller who has abilities that work against City Heroes. His abilities appear to be very strong and Alternerd Reality, one of our fellow Marvel Strike Force & FoxNext Envoy members, is giving him a B+ rating based on first impressions of the kit.
It is not yet clear when Mysterio will join Marvel Strike Force, but it seems logical to assume that it will be in the next 2-3 weeks.