I’m quoting straight from Avid’s “End Of Life” page - Avid list the the Artist Control v2 (both Avid and Euphonix-branded) as having been discontinued since June this year, and the Artist Transport was discontinued in January. The Artist Mix appears to remain on sale for now.
It’s plausible that there are new revisions of the Control and the Transport coming, but it seems unlikely since that territory is now covered by the Pro Tools Dock.
Avid say they will be supporting the Artist devices for another four years though, so not to panic.
To be honest, I’ll probably just keep running my Artist Series kit until I have a really good reason to change. S3 isn’t selling itself to me so far… not for the money they’re asking anyway.