The opening is 2D, but the show is still 3D with seven different storylines. That's why it's called Tales of the Teenage Mutant Ninja Turtles. It's telling different tales or stories with the characters. So season 5 is a different spin which we've seen in the previous Turtles shows. In 2018, there will be a new series currently titled Rise of the Teenage Mutant Ninja Turtles in 2D and unrelated to the current series.