Assuming the rise of 200 feet doesn’t cause the oceanic crust to sink or compress.
Boy, just when I’m start’in to feel good somebody’s gotta come along and spoil it all.
Yes, the conjecture doesn't account for any natural feedback mechanisms, like the one you mention. Way beyond our ability to anticipate, or probably even comprehend.
I wonder how much closer to the sun the earth's orbit would have to be to cause that much melting? The ice (and oceans) are a pretty big heat sink. I think it takes one calorie (not a dietary calorie, a scientific calorie) to raise one cubic centimeter of water by one degree Celsius.
We're talking a lot of calories.