As far as I know from my studies, the Americans have given their President loads of power. It would be quite a challenge to rewrite and redistribute powers of President, should he become a mere Public Figure like the Queen of England. If Americans were to accept undergoing such a change, might as well have more than two main parties and take money out pf politics. I suspect us to be dead by then.
In addition, because there is no clear definition of "high crimes and misdemeanors", congress can pretty much remove The President whenever they want. The House only requires a simple majority to impeach and the Senate requires a 2/3 majority to convict.
It's definitely the most powerful. No one else is even close in raw military power.
Yes in world terms he's clearly very powerful. Compared to the rest of the world a single US aircraft carrier or ballistic missile submarine captain is more powerful than most world leaders.
But his power is very limited. Congress can remove him, they can even completely defund the military if they wanted to.
Our submarine fleet and long range bombing ability are still far superior. Russia and China have near zero force projection capability. Even with surface ships gone, we still have more.
Russia and China both accept that they can't match the US, and all of their strategies for war with us are defensive strategies designed to make it too expensive for us to bother.
No one seriously doubts American military dominance today--not even potential rivals.