GNU Taler is a cryptocurrency platform without the blockchain. It itself is not a cryptocurrency, but the hosters of a instance of GNU Taler can set a currency (cryptocurrency) that will be stored in your GNU Taler wallet. It's currently not being used anywhere as a real currency, but rather for educational purposes (unis, research facilities, etc.) and is experimental. However it has the potential to be a solution for the digital euro the EU wants to have somewhere near 2026 or 2027.
I personally think it has a high chance. It makes the buyers identity completely anonymous from the bank or the merchant using so called "blind signatures", while the merchants incomes are transparent for taxes and stuff. So it definitely is not as private as monero, but definitely a much superior alternative to what we have today in most online or offline merchants. While it is somewhat sad, we all know that monero won't be used anywhere outside of some websites. It's just too slow and people think of it as a investment rather than just using it as a normal currency. Monero is mostly being used as a normal online currency, however with the government disliking it, the fees and usage of blockchain in general make it not very appealing. GNU Taler successfuly found a balance between that, which is why I think it has a high chance of being chosen by the EU.