Bungie did not announce that the last Mayhem week was the last one this Season, like they did announce with Showdown. So I think it's safe to assume that there will be another Mayhem week, next week. However, just to be extra safe, I would suggest going for the Gambit reset too. If you get a team together you can also go for the Trials wins. Mind you here that it requires Trials ROUNDS win. So you only need to win 7 rounds total inside the matches. There will probably be people looking for others for this.