I’ve just finished a writeup of my NWAV ‘cornerstone’ talk. It’s an attempt to try to explain why a particular set of changes took place as the Gaelic dialect spoken in East Sutherland, and studied by Nancy Dorian, died in the latter half of the last century. The explanation, unlike Dorian’s, which relied on primarily sociolinguistic factors, appeals to the weakening and loss of syntactic agreement features, and how this leads to the replacement of a variety of null pronoun structures with alternatives. Which particular alternatives are chosen depends on what I call the ‘syntactic ecology’ of the language.
The draft is on Lingbuzz at:
Structure, use, and syntactic ecology in language obsolescence