Marvel had plans to make Black Panther 3 with Chadwick Boseman prior to his passing, with his contract including an option to return as T'Challa.
Marvel Studios reportedly already had plans for Black Panther 3 starring Chadwick Boseman prior to his passing. Boseman joined the Marvel Cinematic Universe in 2014 when it was announced he would play T'Challa in Captain America: Civil War. He was a scene-stealer in his debut, which increased excitement for Boseman to return in Black Panther. His performance there and in the next two Avengers films further established Boseman as one of the MCU's brightest stars.
The death of Boseman earlier this year came as a complete shock to most of the world. He secretly battled colon cancer for the last four years of his life and believed that he would beat it and continue acting. While many are still processing the loss of such a talented actor and important cultural figure, Marvel Studios has begun pressing forward with Black Panther 2. The story has yet to be revealed, but Marvel Studios president Kevin Feige did confirm they won't recast T'Challa. It was expected that Black Panther 2 would see T'Challa reclaim the Wakandan throne and be set up for an even bigger MCU future.
Prior to Boseman's passing, it appears Marvel Studios was already negotiating his return for Black Panther 3. A story published by THR featuring those close to Boseman sharing memories of the late actor included the tidbit about his MCU future. His agent Michael Greene reportedly negotiated a $10 million payday for Boseman's role in Black Panther 2, which included a $20 million option for Marvel Studios to bring him back for "a then-planned Black Panther 3."
It isn't too surprising to hear Marvel Studios was already working towards Black Panther 3. The first movie was one of Marvel's biggest hits, which is saying something. Black Panther made over $1.3 billion worldwide - the most for any non-Avengers MCU movie - and won three Oscars after nabbing a Best Picture nomination. With Boseman leading the all-star cast and Ryan Coogler back writing and directing, there was every expectation Black Panther 2 would be a similarly-sized hit and do well enough to get Black Panther 3 made.
Without Boseman and the character of T'Challa, it is far too early to know what will happen with Black Panther 3. There is no guarantee that the franchise will continue past a second film at this point. It will undoubtedly be strange to see more installments of the Black Panther franchise without Boseman and T'Challa, with co-star Letitia Wright even sharing the same belief before. Even if Black Panther 3 doesn't happen, the characters from Wakanda could still have futures in the MCU. Disney+ could become the home of spinoff shows or a World of Wakanda movie could be made that expands the scope of the franchise.