With hard headed view, I struggle to see that an independent Scotland will be economically able to deal with large cuts to public sector spending that would almost certainly be required. Per capita spending is already higher in Scotland than in the rest of the UK. Scottish companies have debts denominated in pounds. There would almost certainly be capital flight to rUK. Large businesses may relocate. There is no plan for a new currency, which would leave Scotland either with a weaker currency than sterling, or with a currency it has no influence over.
The UK is obviously suffering economically because of Brexit - an economic relationship that was built up over 40 years or so. Scotland, England and Wales have been a country since 1707. Just imagine the complication of breaking that. It makes Brexit look like a tiny job. Scotland would need to set up mirrors of institutions completely administered by Westminster at great cost, with a shrinking and aging population which is poorer, less educated and less healthy than the rest of the UK, even despite much of the things influencing that (healthcare, education) being devolved to the Scottish government since 1997.
I certainly don’t think it’s impossible. But I think it’s like Irish independence - it took the best part of 70 years for Ireland to economically recover. Over that time there was vast emigration to the UK and the US. Part of that was my own family who moved to the UK in the 1950s because of terrible job prospects in the Republic.