My take is - Corbyn is more progressive than most people. Corbyn represents the most amount of change of any political figure anywhere near power in a long time.
I reckon Corbyn would not mind losing Commonwealth, UK, and everything else, including the EU. Like everything, nato, the lot.
New relationships with everybody, and everything.
If Corbyn gets to be in power, Scottish Nationalists could have a easier path to win a referendum on Scottish Indy.