that will be (for Jolla) the same story then ANDroid (for Google)
an OEM manufacturer selling successfully some device will mean no (or at best little) success for Jolla.
well, they built their business model with that in mind, so hopefully they have thought of a way to profit from it
not providing images for 3rd party devices (N9/50 come to mind) or the SDK with ARM support may be with that in mind.
they want to make sure OEMs have to pay them some royalty to get code.
however that is supposed to work out in the end with FOSS

how was it w/ Maemo / MeeGo?
the images were not FOSS, thus a 3rd party OEM would have had to rebuild the whole OS based on repository contend + rewrite all the drivers.
not impossible, but more trouble then a cheap manufacturer may want (or would even be able to) deal with
see NITroid...
i'm not saying e-yes is cheap or so on the contrary, he is technically brilliant, but still... NITDroid doesn't work smoothly, if at all.