I think it's as simple as Ukraine making a push at Zaporhizia and heading to Mariupol. This will cut the russians in half and cut off Crimea at the same time. The russians want Crimea more than they do Bahkmut. So, they will have to shift their forces from the north to go on the offensive in that direction. When they do, Ukraine will concentrate on taking the Donbas first because Crimea isn't going anywhere and will be cut off from supplies. The winter offensive, IMO, will be in the north and with the arrival of spring, they will move south towards Crimea. One of the main reasons I'm thinking this is that russia is trying to disable the ZNPP. Ukraine will want to liberate that area as soon as they can. When they do, they will continue to Mariupol.