As soon as the Scottish Referendum result came in I knew that the UK union was finished. 45% of its highest ever turnout for a political decision means that the issue was not going away any time soon and that support for the union was on a knife edge, with only a few more heads needing to be turned. Had it been 75%+ i'd have been more assured and done more to care about preserving the UK union, but it's ovbious, for whatever reasons, the people of Scotland do not consider the rest of the UK, particularly England, as a suitable partner anymore.
With or without brexit the nationalists would have continued to chip away at the perceived importance of the UK union and press a case for EU membership as an independent nation. The case for Scottish independence has been made, many Scots have embraced it, and a separation has been on the cards, regardless of the EU referendum result. It's just sped up the process.
So unless Scotland splits in two, with Southern Scotland (the majority of pro-UK support) along the English border, and Northern Scotland becoming independent, it's only going to be a matter of time.
With the Scots rejecting the two main parties, Conservative and Labour, and the sheer size and number of English constituencies far outnumbering anything the SNP could ever hope to achieve, there really is no alternative. The UK union was finished the moment the Scottish referendum was authorised and the result far from conclusive. Unless England gets it's own devolved Parliament, reducing Westminster's dominance, separation becomes a question of when, not if.