I disagree. A victory in the British Isles would completely wipe out the western front, save the French, and I guess British Resistance movements, until America joins. Hitler could send more men out towards the Soviet Union when Barbarossa comes around; Hitler knew he was eventually going to invade the USSR. Plus, I think he'd feel committed to Sea Lion once he started bombing London. Just my opinion.
Some points:
The only really damning event for Germany in WWII is America joining the war in Europe. If Hitler gets smart for a PoD and really wants it, he can prevent it from ever happening, not declaring war after Pearl Harbor, keeping the KM off American merchant shipping, and affecting a defensive stance towards the British Isles. The American people and the Congress won't ever purposefully pick a fight with Germany in these circumstances, either before PH in their isolationist phase, or after PH when they are hell-bent on revenge with Japan, no matter how much FDR may wish otherwise. Without American cobelligerance, the damage that Britain, even with Land-Lease, may do to the Nazi Empire is sharply limited: no invasion of Italy or France, no Torch, little more than a defensive stance in North Africa, a much less effective bombing offensive.
Even the amount of Land-Lease that Soviet Russia shall get in these circumstances is rather limited: Britain is a fellow democracy and an ally against Japan, but the Congress and public won't tolerate that too much American wealth is wastefully diverted from the US war effort in Asia to save the skins of desplicable godless Bolsheviks that are no allies against Japan. A Russia without any hope of a second front and sharply limited L-L is going to fare rather worse than OTL. Although this alone won't likely give Hitler Moscow, Leningrad, or Stalingrad, a Soviet victory (defined as getting any better deal than the 1939 border at the very best) becomes impossible, and even a white peace becomes unlikely. Most likely, Russia and Germany reluctantly sign a Brest-Litovsk peace in late 1943.
As such, the amount of war effort that Germany needs to keep in Western Europe until PH is quite low, little more than what is needed for occupation duties.
The French Resistance movements (or for that matter, in Western Europe, perhaps with the partial exception of Norway) were a tiny fringe of the population up to 1943-44. The Balkans were the only place, outside of European Russia where they purposefully stirred up a hornet's nest with their genocidal efforts, where they faced a serious insurgency from the start. The Vichy regime, like the fascists in Italy, carried at least the passive consensus of the vast majority of the population and had a tight grip on the country. The Western European populations were for the most part fairly content with the relatively gentlemanly German rule, which only targeted Jews and Communist fringes (the Nazis has no racist issues with the "Aryan" Western European peoples, they wanted to coopt them as second-best to the German "master race" in their empire). It is only when things started to look really bad for the Axis in 1943-44, that the resistance started to draw real numbers, which prodded the Nazis to react with their usual brutal methods of repression, triggering a revolt-repression cycle that alienated subject peoples more and more.
After the Soviet Union makes a compromise peace, and Germany is the unquestioned imperial overlord of continental Europe, Britain shall sooner or later be forced to make peace as well by the realization that it is an unwinnable war, and switch back to a Cold War.