> So anybody that will follow, regardless of the person's policies won't matter fully, as that person itself will be replaced 4-8 years later.

That is the fundamental problem. The only way out, is to make changes to the constitution to specifically prohibit the executive branch from having any of this power to arbitrarily change things on a whim. That is the only way international peer could in the future trust an agreement made with the USA.

As long as the US feels it is ok to sign an agreement and immediately violate it, nobody in their right mind will bother to negotiate any future agreements. Which is not a good state to be in.