Given that referendum, an independence referendum was always possible. It was probably only during the 80s that it didn't seem possible, and was definitely being talked about by the time I lived in Edinburgh 15 years ago. Devolution was always seen as a process towards strong local political representation, whether or not ending in full independence (aka membership of the EU).

EDIT: I should note at this point, I honestly don't care how the vote goes and have very little interest in it. To me, it's been a long ongoing process that will probably follow the same rough path and end in the same rough place whatever the vote is.