Glad to hear you're excited for a tournament! There aren't really any tournaments planned for the meantime though. Best guess is the next "official" one will be the fourth 1v1 multiplayer tournament this summer. We've had one every year since 2015, and although Frostfire probably won't be around to host it, I'd be surprised if someone else didn't step up to host it.
So there's your answer. Unless you'd like to set up some kind of tournament beforehand, I think this summer will have the next big tournament.