The question is... What does France do? If lack of Britain causes France to pull support, Germany will push Poland as far as it can, getting both the corridor and basically a puppet, with an ultimate fate similar to the Czech republic. Then probably prepare for war with the USSR because that was always part of the deal.If Chamberlain had allowed Hitler to carve up Poland in half with Stalin, would Hitler have been content with finally retaking the land that was once Prussia and connecting the main German reich with East Prussia? Would WW2 have been ultimately averted?
But if France still supports Poland, Germany still goes through Belgium and that will pull in Britain for sure. Hitler can't delay too long or France will get its shit together.
In any way, war is inevitable. If Hitler declared war against the USSR while still at war with Britain, he's not going to pass up on that war with a quiet west.