Yup, lots of people think like that.
"I'm going to vote no because I don't want to be stuck with Salmond".
The SNP is held together by the belief in Scottish independence. There are many natural labourites, a few tories, some communists, etc. I think many would start to vote other ways. But there probably would be a space in Scottish politics for another left-y party. Lab are getting too far right and SSP etc are a bit strange for the main body of the SNP.