Yes, I fully agree except your last point. I think the expectation what can be called 'strong superintelligence' will rise as well. People will perceive their intelligence boost by supportive aids as 'given assistance'.
Especially in a slow takeoff scenario we will have many tools incorporating weak AI superintelligent capabilities. A team of humans with these tools will reach 'strong superintelligence' in todays standards. In crossover a sole AI might be superintelligent either.

I disagree to draw the baselines for human, civilization and strong superintelligence horizontally. Bostrums definition of human baseline (p62-63):

A horizontal line labeled "human baseline" represents the effective intellectual capabilities of a representative human adult with access to the information sources and technological aids currently available in developed countries.

As information sources, technological aids and communication capabilies (e.g. immersive 3D VR work environments) improve over time, these 'baselines' should be rising, see following figure: