Which part of the Channel coast, though?
It could hardly be the Belgian ports, since Germany has pinky promised to make Belgium whole when the war is done, and not to garrison it.
If it's the French ports, then we really have to be talking
hard peace with France. Like, Treaty of Versailles
hard. Like, Treaty of Tilsit
hard. Which, you know, is not
impossible, even if
@Geon does not seem to be headed in that direction. But more to the point, it's far less likely Britain will quickly make a peace with a Germany determined to chop up Metropolitan France and build warports you can see from Dover with a decent telescope, and not least because fundamentally, Germany has virtually no leverage over Britain*. The Grand Fleet will prevent any possible invasion; meanwhile, the British are free to gobble up their entire colonial empire, and strangle Germany's substantial trade.
The only leverage anyone has mentioned is the threat of holding the BEF hostage. Honestly, I think Asquith (let alone whoever is likely to replace him in such a situation) is less likely to cut a deal to Bring the Boys Back Home than Halifax would have in 1940. But it's highly unlikely in any event. Most of the
Heer is off in combat in Lorraine and northern Burgundy, or investing Paris, and it will take long time for it to redeploy to Normandy, giving the British
plenty of time to react. In any event, a situation where the BEF clearly has no capability of lifting the siege of Paris or making any decisive contribution, is one where we can feel confident the BEF will be withdrawn from Le Havre anyway, or at least, everything but a skeleton force will be.
As for Borneo, I really do tend to think that German interests in acquisitions are going to be focused on Africa. And it's far morely likely a bar tab that France, not Britain (which has suffered no real defeat, and is basically invulnerable to German power), will be forced to pick up. Britain can offer Wilhelm his colonies and his impounded merchant ships back, and that's hefty enough by itself. It will stick in Whitehall's craw (whoever is in power there) to give up territory, even in remote regions, to the Hun.
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* Someone here will inevitably bring up the threat of commerce warfare, primarily with u-boats, possibly even home ported in captured French ports, as would occur OTL in 1940-45. But it will take Germany time to build up such an arm (as, after all, it took time to do OTL), and conversely, a Britain that isn't raising, equipping, and supporting an army of 2 million to fight in France, and does not have to massively subsidize a French war effort at the same time, is going to have plenty of resources to spare to fight a commerce raiding war. Even any possible war with the Ottomans is not going to be a major resource sink for Britain in this scenario.