No way. You reckon all the SNP voters will switch to a mainstream party? Not a chance. Not to mention that labour and Lib dems still have staunch supporters who will vote for them whatever. It's folly to think that simply saying we will cancel brexit will result in 48% of the electorate voting for you. What's more, the other 52% will probably vote Tory.
The SNP is really Labour in disguise. Nicola is very left wing when you listen to her. She hates the Tories with such a passion. Still cannot get over how much the SNP has dominated Scotland and every god damn year all they can talk about is bloody independance.