I just went to the Official Total Drama Fan Group,and found this:
We have an update today regarding The Ridonculous Race. The series will NOT premiere in July 2015 as previously stated. There is a possibility that it will air in the fall on both Cartoon Network and TELETOON but at this time I can't confirm. We do want to apologize for the confusion as I know many of you are looking forward to the new season with anticipation. If you have any questions regarding the change of date, please leave it in the comments, message me directly or email firstname.lastname@example.org and I will try my best to answer your concerns.
I am a little disappointed, but I still have my hopes up for the best :D