It should be noted that Smollett's option for a new season was also picked up, which means he would be available for a series return:
"By mutual agreement, the studio has negotiated an extension to Jussie Smollett's option for season six, but at this time there are no plans for the character of Jamal to return[...]
jamal Archives
Less than 24 hours after Empire actor Jussie Smollett was released on $100,000 bond after being arrested Thursday morning on multiple felony charges stemming from an alleged assault in late January 2019, the executive producers of the popular FOX series have made the decision to remove his character Jamal from the remainder of the series'[...]