What CraigMcCracken probably means by this is that the next PPG will use different styles for different things, chosen by what serves it well. I doubt the new iteration would permanently move to a 3D look for the characters, they’re simply too iconic to ditch.
It might be more like a case where the building scenery is rendered in 3D, which works well with the simplistic, prism-like forms of Townsville’s structures. It could look really cool if we’re getting a lot of destruction in the show.