They'd almost certainly lose the referendum. The SNP is not a very popular party at the moment with the recent corruption scandals, and Brexit and the collapsing price of oil seems to have cooled opinions on how favourable independence would be as well.

Plus, Scotland is seeing huge immigration from England at the moment as living there is slightly less unaffordable, and the English transplants aren't going to vote very much for independence. (There's also no mechanism for determining if someone is actually Scottish, and that was never a requirement for any referenda.)