Johann Lamont resigns because she feels there's too much interference from London, and the Scottish party should be autonomous. The irony!
The ScotLabs are in a policy void, and are a party of political pygmies. There is no obvious successor to Johann Lamont, who was a particularly uninspiring, bitter leader who was more interested in putting down the SNP than putting forward any ideas. They've lost their core support, and I think they are in terminal decline.