By “revolution”, Blackstone is talking about violence and the shedding of blood. The events of 1775-83 would be a good definition of “revolution”.
But by using the term "only after" he suggests that revolution is required for fundamental change of government. My point is that our government was fundamentally changed without one in 1913 when the machinery of government was changed by expanding the federal powers at the expense of state powers.
the 16th and 17th amendments essentially nullified states rights and the proposed convention of the states is intended to undo that