Is there a currency that could replace the dollar?

Yeah, there is no currency that could possibly replace it. Yet people still want to act like the dollar is in danger somehow. Of course if another country arose as a dominant and stable power in the world it would challenge the dollar, that just makes sense.

Is the dollar still trusted worldwide?

There's no other currency in the world which nations prefer as a medium of exchange. The US is the only country with a bluewater navy, which is required for enforcing trade controls. The dollar is still trusted worldwide and more stable. The yen fell over 15% against the dollar in 2023, but the dollar's status as a world reserve currency helped mitigate the losses in other investments, such as oil and gas sales (Russia and Iran), and saved a lot on purchases (China and India, mostly).

Can the dollar replace hegemony?

The dollar's hegemony in finance is partly based on trade. The less that is done in US$, the more challenging it becomes for the hegemony. However, there isn't a strong currency currently waiting to take over. Yet, there is a belief that the dollar is in danger somehow.