Debian Buster LTS is supported until 2024 and then probably ELTS until 2026. Also how many of these 32-bit Atom CPUs are actually in use anymore? It's a pretty edge case.
I run my home automation on atom. Considering that cost of asus eee pc is around $70 it still is a lucrative option of a complete system compared to raspberry.
Debian is (or at least used to be) popular for old hardware - e.g. they supported m68k for longer than most distros. I had an i386 Atom netbook that I was using up until about a year ago, and if I hadn't moved internationally I'd probably still use it.