Lusitania
Donor
British North America received thousands of American settlers who in time became Canadians.The British won't recognize the land title of any would-be settlers, there also won't be any American posts along the way in Louisiana, there will just be French posts and hostile Indians.
America only got the claim on Oregon with the Adams-Onis Treaty, and without that Britain will tell the American government that they'll forcibly evict any potential American settlers there. On top of that, they're going to have a hell of a lot harder time getting there without American control of the Louisiana Territory. And in OTL the only reason the original colonists even survived was because of the good will of the HBC, so if Britain takes a harder line they probably die of exposure and starve upon arrival... if they get there at all.
What was indicated was that yes there would not be American organized system of travel there but the knowledge of the land would exists. Some sort of scheme would arise to take people there. IOTL over 400,000 travelled along the Oregon trail from 1830s- 1860s. What ever trupe of route and system is setup will only bring a small fraction of that.
The west coast is way too tempting to stay empty. Even if settlement starts in 1850s. It will start. What the french can do is setup a route themselves and charge a fee to cross their territory. The British could start settling it themselves and allow small number of Americans to go there even some Germans.
I guess the point I was trying to make was that it would not stay empty just that it’s settlemr pattern be different. They would never be part of USA or even France though.