They are both involved in the Marvel Cinematic Universe, a commitment one would think makes their schedules too hectic for the show.
One aspect keeping Season 5 potentially off the table is the busyness of its stars’ schedules.
Already adding to doubts surrounding a potential Season 5 was Sherlock co-creator Mark Gatiss, who expressed happiness with where the show left off and uncertainty about whether they would do any more installments.
Both Benedict Cumberbatch and Martin Freeman have been super busy outside of Sherlock.