Co-Creator Peter Laird expressed his beliefs in his blog this week over the concern of the Turtles being as he puts it "reimagined as aliens" for the upcoming TMNT movie and agrees with Michael Bay.
Laird posts that he is encouraging all TMNT fans to 'swallow the "chill pill" Mr. Bay recently suggested they take, and wait and see what might come out of this seemingly ill-conceived plan. It's possible that with enough truly creative brainpower applied to this idea, it might actually work. I'm not saying it's probable, or even somewhat likely… but it IS possible.'
He explains that over the years, ideas have come and gone about adding a "fifth" turtle and maybe call him 'Picasso' and how there was a character of "Kirby", 'the "fifth Turtle" that Kevin Eastman and I came up with for one of the several movie ideas which never came to fruition.'
Laird believes that someone has come up with an "genus" idea of having as many Turtles as they want and if each member is an alien race, than there could be a whole planet of them.