They've had their chance at independence amd never do. They always shit the bed. All mouth from the sweaties
But I reckon the goalposts have moved significantly.
After the last indy ref when all these promises were made to them to stay and the second they did it turned into a "what does this mean for England" it caused a massive upsurge in interest. 2010GE only had 6 SNP, 2015GE 56SNP. Part of that will also be down to the collapse of the LD, but normally you'd have expected most to go to Labour. Instead they pretty much all went with a party with one overriding policy.
Brexit is seeing them leave the EU against their will because England has a much higher population and thus drowns them out.
Now you've got a load of Tory (who they despise) charlatans who give the impression they see the other home nations as second/third class turning everything they touch to shit and with such a huge majority likely to remain there for the next decade.
If you gave the Scots and Welsh indy votes tomorrow overwhelmingly they'd leave.