This is a variant of Lyndon Johnson’s iron law of politics: that successful politicians must learn how to count.
You need to find enough of stakeholders that will accept your Architecture design. One way of doing this is to present a hypothesis to them and see how they react.
However, the classical situation is when the stakeholders not are aware of the underlying problem or denying there is a problem. Without a majority of accepting this, your hypothesis will not fly and there will be no change.