It doesn't matter who becomes leader of Labour. They will now be about as relevant as Woolworths.
Not true, that. They're still the second-largest parliamentary party by a long way and will lead the official opposition. Barring something happening which resembles the collapse of PASOK and rise of Syriza in Greece - which, let's face it, is deeply unlikely - they're going to remain so for the foreseeable future.
I can see them going for someone relatively young, and not associated with the last Labour government. Either that or Burnham, or conceivably Chuka Ummuna.