The fact that this is a pretty big incentive to change the situation of "some people [having] no choice but to use flash".
If a company has no plans to use these premium features, then yes, I would imagine they will continue along as-is with Flash.
But a last thought; a revenue sharing plan like this will make big players nervous - what might Adobe starting charging for next? It will cause developers to start at least considering alternatives.
Adobe seems pretty desperate here.
In the meantime, it seems like a lot of unity devs are trying to figure out ways to get Facebook users to install the player through sneaky methods.