I don't think it's necessarily inevitable, but a lot depends on the factors that you already listed.
Starting out with 120 pounds to lose and being over 40, I stand a good chance of winding up with extra skin, but I'm doing what I can to help minimize it (exercise, losing slowly, drinking plenty of water, etc...) and I'll worry about it when I get to goal, which at the rate I'm going will be at least another year.