Quoted from Eryeal:
I think we are a LONG way away from CGC actually writing new game code for games (ie improving). Sure they can squash some original bugs, or make basic changes like lighting, etc. But actual NEW code that adds modes/features to the games? I don't think so. Regardless of how it turns out, can you imagine the backlash from actually changing "classic" games? Sure there are some exceptions out there, such as CCC, but that wasn't done by a pinball manufacturer. I don't think there's any way they risk changing any classic games other than very minor stuff.
If they make changes of any significance to any of the games they will be wise to include a setting to play the original code as well