In thinking through who may launch to high-inclination orbits from the Cape, I totally forgot about DARPA’s XS-1 that will be based out of Cape Canaveral. I would be surprised if there weren’t plans to launch XS-1 from Vandenberg, but as of yet, we haven’t heard anything. Maybe the Department of Defense had XS-1 in mind when developing a polar corridor from Cape Canaveral?
The trouble there is that XS-1’s payload to orbit is already fairly low—1,360 kilograms—and launching to polar orbits from the Cape will lower that even more. That said, a few hundred kilograms to high inclinations would be competitive with Electron or LauncherOne-class vehicles.