Ultherapy of the neck will help with the sagging skin of the neck. Unfortunately, it will not completely correct the amount of laxity that you have. Only some improvement can be expected. A necklift would be more effective in addressing the residual skin laxity of the neck. Best wishes.
I appears that you have fair amount of skin laxity. I do not think that any non-surgical treatments will make appreciable difference. I would consider revision face and neck lift with possible fat grafting.