Dimitri's proposal is about ending 32-bit Ubuntu Desktop ISOs and would not affect other flavors of Ubuntu and the 32-bit multi-arch packages would still be maintained. He argues that all currently shipped hardware that's fast enough to handle the Unity desktop is likely x86_64 while being with i386-only hardware in 2016 are unlikely even able to run the latest Ubuntu desktop releases with a fluid experience.
Thus he's started a public discussion about ending the Ubuntu Desktop 32-bit ISOs via the Ubuntu-devel list.
For years there has been calls to end Ubuntu for x86 32-bit to not much avail. However, with Ubuntu 16.04 LTS coming up, it would be a perfect last release to afterwards end the 32-bit official Ubuntu desktop ISOs. Those with old x86 hardware could either stick to an LTS release or try out an alternative flavor like Xubuntu/Lubuntu or another distribution.