The currency question is the without a doubt the biggest obstacle. I saw one poll where only 18% of Scots would accept adoption of the Euro. I've come across a number of articles and analysis about potential EU membership and the consensus is that Scotland would be admitted after a period of 3-8 years following independence, almost all however placed a high importance on Scotland adopting the Euro.
Fear of what would happen with currency has always been a major stumbling block for the Quebec independence advocates here. After all most us can get pretty damn sensitive about our stash.
I don't think independence will happen, but with Johnson in charge there is always the possibility of him mucking it up.