I think many in this thread are missing what's happening in the UK. This isn't just about Labour or the Conservatives losing votes, it's about a growing feeling in the UK that the two party system doesn't work. Labour and the Tories have for decades taken voters for granted, increasingly people are choosing alternative parties - that means no more majorities for either.
Scotland has simply moved faster than the rest of the UK due to the behaviour of both parties around the referendum, but the rest of the UK will catch up and you'll see a lot less of the vote going to the tories/Labour this time around.
It's not about any one party, it's about their attitudes to the electorate and how for decades they've seen themselves as managers of the UK, rather than answerable to the electorate. the SNP may be reaping rewards in Scotland this time but it could easily enough swing elsewhere next if they don't work properly at Westminster.