[2020] Can you still complete "The Eternal Traveler" quest?

Yes!

In addition to soul-bearers on mortal worlds, we’re making sure that former-soul-bearers in the Shadowlands drop the pieces that the Eternal Traveler wants. And that will include former-soul-bearers in Shadowlands dungeons and (later) raids.

We’ll note the addition of the Shadowlands drops in our hotfixes update once it’s complete.