You are not required to accept anything other than digital ids. So from experience, whatever demands euid has will be what is required to identify you.

If they have to support something that most everybody has they will soon stop supporting alternatives that are not required by law. What then?

My prediction is that eventually services for people NOT using the digital ID will be so degraded to be almost useless or seriously disadvantageous.

Kinda like the discrimination DB does for people using paper tickets vs those using the DB Navigator app.