The central weakness in the SNPs belief in the inevitability of independence is the nature of the SNP vote.
The SNP make much of their electoral success, whilst never reflecting on the fact that certain areas that are now considered key SNP safe areas, are also No voting, and going on a crude class basis, the sort of rural, middle class seat which used to habitually re-elect Conservatives or Liberals.
I have no doubt the SNP will skate this election, and I equally have no doubt that many people voting SNP on their managerial record wouldn't consider voting Yes to independence in a new referendum.
I'm prepared to be proved wrong, and as a Yes campaigner and natural pessimist, I'll be happy to be proved wrong, but I don't see any evidence that the No vote from the referendum has crumbled to any great extent and barring some exceptional political upheavals or contingencies, I find it unlikely there will be any fresh referendum within the next 5 or 6 years.