Out of the 28 members of the European Union, 19 use the Euro as their official currency. Two are exempt from adopting it (Denmark and the UK). If all remaining 7 (Bulgaria, Croatia, Czech Republic, Hungary, Poland, Romania and Sweden) adopt the Euro by the end of 2022, this question will be resolved as "Yes".
In the case any member leaves the EU, this question will be resolved based on the remaining members. That is to say at any moment between now and the end of 2022 100% of the EU mambers (with the exception of Denmark and the UK) have the have adopted the Euro as their official currency for it to be resolved as "Yes".