Long story short, starting with Ubuntu 17.10 (Artful Aardvark), Canonical won’t offer ISO images for the i386 architecture for the Server (classic) and Desktop versions, but they will continue to provide security updates for existing 32-bit installations via the main Ubuntu archive, as well as Ubuntu Core, Cloud, Container, NetInst, and Server (subiquity) images. At the moment of writing, no official Ubuntu flavor announced that they’d follow suit and drop support for new 32-bit (i386) installations starting with Ubuntu 17.10 (Artful Aardvark), which hits the streets in three weeks, on October 19, 2017. Flavors like Lubuntu and Xubuntu, which are designed for old computers, most probably won’t drop 32-bit support anytime soon.