Basically snp would become something similar to the scottish greens minus most of their policies to do with become carbon neutral by 20XX. Tories would probably split into the right wing party of the new Scotland and the reunification party of the new Scotland. Labour would exist and might not really change from the way it is right now other than its no longer attached to the Westminster Labour and they have to decide if they still want to be part of the union or to accept that we've left. Liberal democrats might become similar to what the SNP may become but that really just depends if they decide to accept independence or if they still want to be part of the UK.