The type of barrier is irrelevant to this discussion.
When you say the list has been superseded, do you mean we found new rishonim?
The Mishnah Berurah was only following the Mishkenos Yaakov and we know today that the overwhelming majority of Rishonim maintain that shishim ribo is a criterion of a reshus harabbim (see http://eruvonline.blogspot.com/2009/06/reprinting-of-berlin-edition-of-behag.html).