Actually the SNP didn't even think they would get independence at the start of the campaign, the yes vote only managed to pick up momentum a few months before the actual vote. IMO the NO vote only won because of the promises of further power given to Scotland if they voted no.
I will say this though if things don't change or don't change enough a lot of people on both sides of the vote will be very angry and will end up in demonstrations like what happened in HK.