Yup, what is goal? There are as many answers as there are people here.
If you're talking about weight, the number on the scale, I think many people set goal at a normal BMI. It's important to understand that is not realistic for everyone. Average weight loss with a DS is about 80-85% of excess weight. Some lose more, some lose less.
BMI isn't as meaningful (it's arguable if it ever is), but so much less so to us once we become morbidly obese. Our bones and vascular system get heavier. We have excess skin. Lots of people feel they look too gaunt and sickly at a "normal" BMI if they lose down to it.
Everyone is individual. It's also not a race. I've seen people lose fast, and bounce back. I've seen people slowly drift down. I've seen everything in between. It really doesn't matter.