Complex sentence: In December 2017, it was reported that NBC is developing a revival of the series planned to debut during the 2018--19 television season and will feature a mix of original (excluding Steve Carell) and new cast members.
Split into simpler sentences: In December 2017, it was reported that a revival of the series is under consideration by NBC. It would debut during the 2018--19 television season and would feature a mix of original (excluding Steve Carell) and new cast members.