Wasn't Turtles Forever supposed to be a series finale "movie" of the series anyways?
Or maybe I'm reading this incorrectly, are you asking for a movie that has numerous elements and a tone from 2K3 and
has its own universe OR a movie that
has continuity with the 2K3 universe (which would make it a sequel to Turtles Forever then)?
Because if it's the first option, then... couldn't somebody argue to consider the Mirage source as well since 2K3 has a significant amount of Mirage elements that were modified for an audience of kids? ...Then it would lead to comparing it to the 1990 movie, in terms of the direction of the plot and how substantially different they are.
But for me, I wouldn't care for a 2K3 movie because although the story writing was superb, the characterizations and melodrama are what drag it down for me, with 2K3 Raph and Mikey being the most loathsome to me (with Raph being a rageaholic and Mikey's loud idiocy), how brutish 2K3 Casey was depcited, 2K3 Leo having too much screen time and character development compared to the other Turtles, and how the melodrama undermines a lot of the show's serious tone and makes it unintentionally hilarious (funnier than the actual designated humor within the show). In addition to the annoying, constant reintroduction of a newer "badass" Shredder within the series (Utrom Shredder, Cyber Shredder, Tengu Shredder, Karai Shredder, etc.). I'm not saying I wouldn't watch it eventually, but I certainly wouldn't be enthusiastic to see it.