... update from code4lib slack (since this post has circulated): it sounds like the conference organizers are considering alternative venues, and that the conference will likely be fully virtual if that falls through.
... despite CMU's decision it looks like the code4lib 20215 conference IS ON
https://lists.clir.org/cgi-bin/wa?A2=ind2512&L=CODE4LIB&P=40998
in #philly