The Challenge Season 27, “Bloodlines”, doesn’t even have an official air date yet, but early speculation for Season 28 has already begun. Word is that first availability calls have already gone out, not all calls have been confirmed though. A list of potential cast members who received calls has been composed and it is an interesting mix (see list here, http://vevmo.com/forums/challenge-fall-2015-early-cast-speculation). No theme is confirmed yet and there will undeniably be many more availability calls to go out. The filming for Season 28 right now is planned to occur during November and December. This would leave only a three month gap between the filming of Season 27 and 28. A gap this short hasn’t happened since The Ruins (Season 18) and Fresh Meat 2 (Season 19).
Some of the people who have already received an availability call are quite intriguing. Brad, from Real World: San Diego, got a call and we haven’t seen him since he won Cutthroat (Season 20) with his wife Tori (Road Rules: Viewers’ Revenge). Brad was always a great challenger but he and Tori have two young sons now, so I’m not sure if he would leave for a challenge or not. Another interesting former challenger who got a call was Jenn from Real World: Denver. Jenn has not been on since Rivals (Season 21), but has received availability calls for several challenges following Rivals. I follow Jenn on Instagram and she is in amazing shape. She has been coaching CrossFit and looks challenge-ready. If she does decide to make a comeback she could probably perform exceptionally well.
Another question about potential casting is whether or not producers will include the “Bloodlines” and cast members from Are You The One 3. Season 27 will most likely be passed off as a Fresh Meat 3, so if producers like some of the “Bloodlines” I wouldn’t be shocked if they got called to do more challenges. As for AYTO3, cast bios have been released and I would think the season would air sometime this fall. With such a short gap between challenges, I am not sure if AYTO3 cast members would be added or not. If they were to include people from AYTO I would think they would stick to seasons one and two until season three has finished airing.
As for now, this is all just speculation and it is quite early. More information will be exposed leading up to the departure date. Nothing is confirmed yet, remember that.