neko, I hear your point about not changing curriculum...I'm assuming you mean the 12-kata 'standard' Goju mix. but is it really the kata curriculum that define a style? If a Goju school chooses to concentrate on Goju's 4 core kata (and all might not agree which those are), can't they still justify calling it Goju? I think they can.
Goju's main philosophies are a blend, and it's that blend which makes it Goju...not which combination of it's individual pieces.
Changing curriculum isn't the problem... it's prematurely changing things when it starts to go wrong. usually from incomplete training. It's not impossible to imagine someone having a sho-dan or 5-10 year knowledge of Goju, then independantly opening up shop. Is it Goju? sure, but perhaps only for mudansha students. If that owner decides to bump his own rank, lets say to go-dan...the advance training he is giving his yudansha is with a pre-shodan level of understanding in Goju. - since that is as far as he was instructed. people can't teach what they don't know.
...and when he/she starts changing things just because they can (or eliminating kata from the syllabus since they never learned it), thats when it starts turning into something other than the base style's philosophies.
On the opposite end, if someone is well trained in Goju and understands it, they may find in their continued research and teaching experience that adding/removing a drill, kata, bunkai kumite, etc may better fit the needs without comprimising the fundamental philosophies which make Goju a style.
so for advanced levels, for example if you learn and happen to study a white-crane kata which is not on a goju syllabus, but you study it long enough to see common principles to Goju...then when it comes your time to teach, you may choose to teach THAT kata at advanced ranks instead of a 'standard'.
Just some thoughts to add to the black or white thinking that kata / curriculum / styles should never change.