Honestly I can't see any candidates to actually replace the dollar. To become the world reserve currency the issuing country has to be very stable, make their capital markets as open and transparent as the US, accept running a large trade deficit and issuing government bonds to almost anyone no matter the geopolitical situation.

China is stable, but without a regime change they are not at all interested in opening their financial markets. India is large and a little more open, but the big question mark is stability (both external wrt Pakistan/China and internally). The EU could do it but first they'd have to get buy-in from the export giants which seems unlikely and they'd also strain the relationship with the US.