Please let's not speculate here about any issues that dual US/EU citizens may experience traveling to or from Europe once ETIAS is implemented.
Let's wait until the rules and regulations are in effect and discuss actual members' experiences and solutions.
In the meantime, if you wish to debate or speculate how ETIAS may affect dual citizens, please do so in the following thread in the
Checkpoints and Borders Policy Debate forum:
TWA884
Travel Safety/Security co-moderator