Pic: A Force For Good at our 'Get Sturgeon Telt' rally when she spoke in George Square on 2 Nov 2019.
The "independence" debate is framed by the nationalists deliberately as "Scotland becoming independent by leaving the UK". This implies that there would still be some kind of "United Kingdom" left after Scotland departed. In a way, this makes the whole matter appear less dramatic to some people currently living in "the rest of the UK".
It is not a true description of what is actually at stake!
It tends to lead to a complacent attitude among many in the British political establishment. This is worrying to those of us who do realise what is at stake!
From our way of looking at things, it is not so much about Scotland "leaving the UK", as the UK itself being destroyed by Scotland's departure.
Consider our history.
The United Kingdom began its life as a Parliamentary State, with the union of Scotland and England on 1st May 1707. At that time, England had already incorporated the principality of Wales into the wider English State (under Henry VIII in 1535 and 1542). Ireland joined the UK in 1801, and then part of it broke away in 1922.
So the essence of "the Union of the United Kingdom" is primarily the Scotland/England union.