Despite having it's current eighth season broken up by the COVID-19 delays (Only three episodes have been aired since the Fall), NBC is committed to continuing the relationship of Liz and Red, it seems. It's been confirmed today that The Blacklist will be returning for a season 9 by it's network, NBC.
NBC, known for it's long-running scripted series (They are the home of both the Law & Order franchise and the Chicago franchise), has the show in the Friday night slot, often where shows are put to end (Referred to in some circles as the "death slot"). But, like "Supernatural" on the CW, the show has continued to bring in healthy viewership. The first two episodes of season eight, which premiered last Fall, averaged over 7 million viewers (Including with delayed viewing) along with being highly popular on Netflix (Who own the streaming rights).
So, if you're hoping for there to be finality on Red's identity any time soon...it's probably not going to happen. Stay tuned!