Can't go out of date – great idea!

This looks like a great plugin! I was looking for a “nofollow” plugin and was considering “Nofollow for External Link”. The only thing is programs like that nofollow everthing. Also, can’t those other blanket application plugins go out of date or quit working with WordPress updates? In my beginner understanding of WordPress, once the nofollow code is added it will always be there unless you remove it, right?. WordPress updates can’t change that. I have limited external links right now so going back and “nofollowing” them was easy.