Season 2 of Star Trek: Picard is tentatively scheduled for return in early 2021.
Admiral Picard had assembled quite a team by the end of Star Trek: Picard. With Seven of Nine, Captain Rios, Aggie, Raffi, Soji, Elnor, and himself, they were heading off into adventures unknown. But a need remained when the credits rolled. Though the ship belongs to Captain Rios, the missions do not, and if Picard is to be the leader, he needs a second in command, someone with experience and who is more familiar with duty and fighting alongside Picard. Lt. Commander Worf would fill that space.
Though the current team members are behind Picard, they are individuals who have been brought together out of necessity. And none of them are guaranteed to remain with Picard. Seven of Nine has her own desire to eradicate wrong by whatever means necessary. Captain Rios doesn’t seem to be the type who likes to take orders. Raffi loves Picard, but she has demons to slay and will likely want another chance with her son.
This doesn’t mean that any of these characters will betray Picard, but they aren’t necessarily a cohesive unit yet. And Elnor needs someone to guide him more than Picard can. Someone like Worf who is a trained warrior and can teach him when to fight and when to stand down. Worf has been in command and would have no problem standing behind Admiral Picard.
With Data gone and Riker married and content with his life on Nepenthe, Lt. Commander Worf seems the logical choice. Combine that with his knowledge and skills, he would be a formidable second in command. And even though this isn’t a Starfleet crew, Worf would be invaluable because of the time he spent working with Picard, his knowledge of how the former captain operates, and also as a strong leader to bring the team together as a unit.
Even if Worf wasn’t a series regular, it would be beneficial for the crew to see his interaction with Picard and to experience how they work together. It would help them gain a better understanding of how they will need to operate on missions as there can’t be more than one person in charge.
While it’s entirely possible having Picard in command isn’t what the writers or producers have in mind, it’s hard to believe a series with a former Starfleet captain and retired Admiral as formidable as Picard would want him to be anything but the leader. And every leader needs a second in command.