Bobbi Morse (Adrianne Palicki) and Lance Hunter (Nick Blood) left Agents of SHIELD in season 3 because plans for their spinoff show, Marvel’s Most Wanted, never panned out. Introduced in season 2, Bobbi and Hunter quickly become fan-favorites, especially because Bobbi was based on Mockingbird, a well-established character in Marvel comics.
Hunter was originally introduced to the show as a mercenary working with Isabelle Hartley (Lucy Lawless). Bobbi was introduced as an undercover agent infiltrating HYDRA, with the additional reveal that she’s Hunter’s ex-wife. Despite their characters’ popularity, they left the show halfway through season 3, after a mission in Siberia gone wrong led to them being forced to leave SHIELD.
Bobbi and Hunter’s exit was meant to set up Marvel’s Most Wanted, a spin-off series focused on the two characters. After two attempts at getting the show made, including a filmed pilot, it was turned down by ABC both times and the show never aired.
The first real attempt to get Marvel’s Most Wanted made came at the end of season 2 of Agents of SHIELD. The season 2 finale set up Bobbi and Hunter leaving SHIELD, but when ABC passed on the show, they were quickly written back onto the show. A much more serious attempt at the spinoff was made in 2016, during the third season of Agents of SHIELD, with the show getting a pilot order, not just a backdoor pilot in an episode of Agents of SHIELD. A story in the middle of the season set up Bobbi and Hunter’s permanent departure from the team, taking the fall for a mission gone horribly wrong, to head into the spinoff.
Most Wanted seemed like a pretty smart bet at the time, with Marvel’s stock doing quite well on TV at the time. Agents of SHIELD was coming out of its third season and Agent Carter had just finished its second and final season, Daredevil and Jessica Jones were both going on Netflix leading up to The Defenders, and Cloak and Dagger had just been greenlit at Freeform. In May 2016, however, Most Wanted wasn’t picked up to series by ABC, and even though they left the door open to shop it to other networks or streaming services, it never materialized. The pilot hasn’t even been shown anywhere years later. While the show never materialized, that didn’t necessarily mean the end for these characters. Bobbi hasn’t appeared in anything Marvel since her departure in season 3 (though Adrianne Palicki did want to return for a spin-off), but Hunter made an appearance in season 5 episode 5 of Agents of SHIELD, “Rewind”, helping Fitz get to the future to reunite with the team.
There’s also the possibility of different incarnations of these characters played by different actors. While both are from Marvel comics, the versions from Agents of SHIELD aren’t the most faithful to the comics. A different Bobbi Morse could appear in the Disney+ Hawkeye series, given her close ties to Hawkeye in the comics. Another Lance Hunter could appear running a British version of SHIELD, more faithful to his comic counterpart, without directly referencing this Lance Hunter. Since it’s unclear how canonical prior TV series are to the MCU, they could easily reintroduce Bobbi and Hunter or any other Agents of SHIELD characters in new places without any big continuity hiccups.