I doubt we see many if anyone pre BB10 contacted and few BB10-15. I'm expecting mostly people from seasons 16-21 and nobody from OTT even though Alex and Shelby DESERVE.
BB21: Nicole, Tommy, Christie, Kemi (if they decide to market it more as a second chance and not all stars)
BB20: Kaycee, Tyler, Angela, Brett, Haleigh
BB19: Josh, Christmas, Alex, Jason, Cody, possibly Paul if they're going for 3rd timers.
BB18: Nicole, Victor, Natalie, Paulie, Da'Vonne, James, Frank
BB17: Steve, Liz, Vanessa (but she wouldn't do it rip), Jason
BB16: Derrick, Cody, Caleb, Frankie, Zach, Donny
BB15: Andy (if other winners say no otherwise they won't ask him), Elissa
BB14: Ian and all of the returnees from this season except Boogie and Janelle. I doubt we see anyone from All-Stars 1
BB13: Honestly probably none of the noobies. But maybe Daniele.
BB12: Hayden
BB11: Kevin
BB10: Keesha PLEASE GOD LET HER BE ON THIS SEASON. Oh and they probably asked Jessie Godderz flop ass too.
theres someone on clubs alleging they have a source saying pre-allstars ppl were contacted and im pretty sure april lewis has been close to getting on some of the recent mix of newbie/returnee seasons so you never know!