Due to declining usage of Arch Linux i686, they will be phasing out official support for the architecture. Next month's ISO spin will be the last for offering a 32-bit Arch Linux install. Following that will be a nine month deprecation period where i686 packages will still see updates.
From November onwards, packaging and repository tools will no longer require i686. Thus from there it's left unsupported, unless there is interest from others in keeping Arch i686 alive where it could then become a second-tier architecture.
Details on Arch Linux preparing to kill off i686 support can be found via this mailing list thread. Hopefully we'll see other Linux distribution vendors do a similar maneuver this year!