We won't cancel Muric's loan. He is NAC's starter this season and it's better that he stay on loan. City obviously rate him higher than Grimshaw, but I don't believe there's going to be a noticeable difference at their age. Neither are good enough or ready to be our keeper and neither is an ideal cup keeper so it would be pointless to do it.
My guess is that Ederson just plays most games. Could let Grimshaw play the first rounds of the League Cup or FA Cup depending on the opponent. I suspect we can still sign a free agent but there really hasn't been much discussion about when the cut off is (or if it was the start of the season or not). It used to be that you could still sign them after the transfer window had closed but I haven't seen any sort of confirmation if that is still the case.