HMMMMMMMM this is very reminiscient of anime style compilation movies.
What I would imagine this to be if someone actually wanted to make this happen.... I would see three scenarios
1) Taking the old footage and "remastering" it, similar to Dragon Ball Kai, they would probably have to redraw some scenes and it may look bad like.... Flash art style (we had a taste of this in the 2012 cartoon...). The cast would be accessible.... so this is not too far from reality.
2) Brand new anime like adaptation using an anime studio. Assuming the old cast can do work on it, this may work? But getting a studio interested in this and also have a Japanese adaptation may be hoping for too much. OVAs aren't out of the question, but would require either a lot of money to promote it again or more merch.
3) Then there's the remote possibility. Old style animation with new style techniques. This is similar to Universal Century Gundam animes -like Gundam Unicorn... using the old aesthetics with modern techniques. This is what I would like to see. But TMNT wont' get this kind of love.
For this last option, I'd imagine that they would modernize some of the first season's dated things.. like gun control. Remember that old lady with the machine gun... she'd have that, and two more hand guns.
