To be honest, I don't get the feeling that Corbyn is fussed enough about Brexit to compromise on his current stance. Firstly he's a Brexiteer. Secondly he leads a party who's electorate is pretty divided on issue, so no need for him to over-extend to either side. Thirdly if a no-deal Brexit happens and is (inevitably) greatly damaging, he hopes he can milk it by pinning it on the Tories. So I reckon he'll just stick to it, until Brexit happens.
I don't see Tory MPs rebelling to the point that they give him the keys to #10, so that'll be that. Personally I think Ken Clarke in a temporary government to avert no deal makes sense. It's still a Tory MP, so it will entice Tories to rebellion. His stance will anyway be moderated by the fact that the bulk of his support would be coming from Labour MPs who could withdraw support any minute and bring it down.
What matters more is the remit of the temp govt. They all agree on applying for extension to avert no deal. But then Corbyn wants a GE, Swinson wants a referendum and god knows what the Tory rebels want.
I think it's just a countdown towards the inevitable.