The SNP had the commonwealth games, a Tory govt imposing austerity measures left right and centre, a huge very visible campaigning machine, two of the most shrewdest politicians in Europe in charge and could only manage 45%. England voted brexit and the polls still barely moved.
How that will change to polls consistently showing 60% yes(which is what will be needed for Sturgeon to feel confident enough to call the vote) before 2020 is beyond me. The best hope for Yessers is that there's an administration at holyrood that can be seen to balance the books well enough when they get more tax raising powers. Only thing is, the SNP don't want them!