Tom says he can't create a new season for now due to a lack of marketing.
But if that changes sometime during this decade, my hopes are that the sixth season should go for the 20+ cast, rather than 10+ cast (like have a big returning cast).
Maybe they should give the show one more season to finally answer the questions that have gone unsolved since TDPI ended (like maybe give Chris a backstory on why he became the sadistic host he is today, have him actually finally allow Courtney to make it into the final 2, have the female blonde campers last longer, etc.) It should be called Total Drama Grand Finale.
Also, another season of the Ridonculous Race would be nice. I would like it if the next season did 20+ teams rather than the usual 18. There would be 24 teams of 48 racers. I would like it if there were a mixture of returning pairs from last season competing against some new original teams (teams that could use another shot at the million like the Police Cadets, the Sisters, the Best Friends, and the Ice Dancers, and some teams that originally were supposed to last long previous season but never did like the Fashion Bloggers and the Geniuses are fleshed more). The new teams would consist of some new original pairs (roomates, lifeguards, etc.) and a few new Total Drama teams (such as Katie and Sadie and Amy and Samey). There would be 26 new destinations visited. The premiere's location would be set in New York City (the same place where Don took the final 3 teams to). I think this season should be the final season if it involves returning teams and new teams. Also the season finale should not end on a cliffhanger. Have Terry McGurrin's character say in the lines of "anyhow the show is over. So I hope you enjoyed another action packed race around the world, right here on...The Ridonculous Race!" thus it would finally conclude the spin-off series.
Anyway that's my thoughts if the creators plan anything new since a toonzone user named Shadow Beast mentioned the creator still having plenty of time to chunk out new ideas, be it this show, Total Dramarama, Lucas the Spider, and future projects yet to be revealed.