The second season of Peacemaker recently came to an end, and according to the series' creator and DC boss James Gunn, it seems to be the last, at least for the foreseeable future. That said, we haven't seen the last of either Peacemaker or his friends from the series.
On the contrary, Gunn has said several times that they will be important going forward, which presumably includes the upcoming Superman sequel Man of Tomorrow (it has already been confirmed that the ending would lead up to that film, and now that we've seen it, we can imagine why). Another example is the upcoming series Waller, which is closely intertwined with Peacemaker's story.
The idea was that it would have been released before the second season of Peacemaker, but that didn't happen. Fortunately, that doesn't mean it's been shelved. In an interview with Emergency Awesome (thanks, Yahoo), Gunn says that the script is being worked on and that the series will be about what Waller has been up to during her absence, up until Man of Tomorrow.
If we haven't seen Peacemaker and the others before then, we can expect to see them in Waller. Viola Davis is expected to return as the titular character, whom she first played in Suicide Squad in 2016 and has since played in the sequel The Suicide Squad, Black Adam, Peacemaker, and Creature Commandos, and is likely to continue to appear every now and then, including in her own series.