When I first saw this Tweet, I assumed the issue would be resolved:
And it has:
In response to the concerns raised by ourselves and the wider community, the Ubuntu project recently discussed a more conservative approach wherein a selection of 32-bit libraries would still be available on the host system, through at least 20.04 LTS.
I don’t understand the technical issues here, but coordinating projects is hard and sometimes you need a dramatic announcement, like Pierre-Loup’s, to get everyone to see the challenge and get on the same page. So I’m happy things worked out.
Update on Steam, Ubuntu, and 32-bit support | Steam for Linux General Discussions