I've used Tabletop.TO to run many, many Legion events and it works great. You can create travel/play groups to keep players getting paired against their usual opponents in the first round. Players can upload lists, which can be hidden until the day of the event. Tabletop.TO also does push notifications for table assignments as well as 2-party reporting for game results. You should use the FFG 1.1 rules.

Asmodee own Atomic Mass Games as well as FFG, so Asmodee isn't "dropping" the games, just moving the license to another subsidiary.