How shocked would you be if Whites actually started rebelling against the systems and institutions of White domination and oppression? Eg. Congress, Wall Street, KKK, etc

It depends on the scale of the rebellion, because there have always been Whites who rebel against the Systems and Institutions of White Domination, for various reasons.  Some rebel because they seek to redirect the System, to replace those at the helm of the System, or because they are sick of dying for the System, or because they feel they don’t get their share of the spoils of the System.  Those are just a few reasons. 

There has always been White Rebelling, but not on behalf of the non-White victims of the White Domination, those who rebel on our behalf are very rare and far between.  So, I’m not surprised when Whites rebel, not at all.  That’s why we shouldn’t confuse White Rebelling against White Power,
with Whites being allies of the rest of humanity.  Some are, but most
are not

If there was a wide scale rebellion against their Systems and Institutions, I’d be surprised however. 

Generally, when shit gets fucked up enough for Whites to rise up on a large scale, they tend to rally around their Systems and Institutions, not rebel against them.  That’s a Consistent Historical pattern.  Congress, Wall Street, and even the KKK get more blind support from the White masses in times of great stress and social upheaval.  The White masses tend to be more independent and even rebellious when they have more agency, security, and independence; not less. That’s why even the White masses are kept in a state of relative economic and social insecurity, so that they can be better controlled and manipulated by their Elites. 

Whites lean towards Fascism and Militant Nationalism when shit gets too fucked up for them, they don’t try to tear down the Systems, they prefer to scapegoat vulnerable populations, attack them.  The White Elites know this and fuel this impulse of the White masses.  But there’s always a segment of Whites who see through the Bullshit, these Radical Whites are often attacked by the White masses as aggressively as the non-White scapegoats.