What do you mean by “self adjusting just intonation”? Presumably you would need to sequence the desired key changes in your song, because I don’t think you’re going to want software to attempt that automatically. And it can get more complicated than that. I can imagine songs where you would want a melody note in one key to be sustained while the rest of the harmony transitions around it into a new key, which is also something that I can’t imagine being done automatically right now.