The chance of the dollar losing its reserve currency status is slim-to-none. No matter how bizarre the US is, nobody trusts the Chinese Communist Party (CPP). And although the US can manipulate the value of the dollar, its tools are limited compared to the CPP.
Plus, the US is still the only country that's willing and able to prop up the world financial system with no immediate benefit (see Argentina). The US can and will intervene when necessary. And as history has shown, the Euro Zone can't really make decisions quickly and effectively. How many times has the Euro been on the verge of collapse in the last 20 years? And is proximity to Russia is, well, risky.
In any case there is no currency big enough to take the dollar's spot at this point in time. Trillions of dollars flow through the financial system every day.