I'm also glad that Yes didn't win in 2014. I think both Scotland and the rUK would have been the weaker for it.
However, I think his premise is flawed. The SNP would have self destructed fairly soon after independence had been achieved. The SNP is a single issue party and, as such, it attracts people of many different political persuasions who all have one aim in common. Take that aim away and there is no coherent direction for the party. It would be guaranteed to fragment, and I think, pretty quickly.