The abandoned clause would have meant that JoCo would have been elevated to shadow mayor, meaning even greater powers. This will now no longer happen, which is a very good thing.
Collins is on record as being against elected mayors so he will presumably be pleased. My theory is that this is because he would face the choice of running for the job himself (once the shadowship had ended obv) or seeing most of his powers go to someone else. His failure to secure the nomination for the Nottingham East parliamentary seat suggests that he cannot bank on even getting Labour's support for anything beyond his little St Anns burrow, never mind