I'm curious as to whether they've quietly abandoned it?
The last (and really, only other public) effort they seemed to have put into it, were to QF in the early days of Project Sunrise. Haven't heard a peep since then.
The reason I even ask, is because a poster on another thread wrote in and received (what we're taking to be) confirmation that the aircraft marketed as an ACJ350 to the German government, is actually a standard A359. The interest there is that the ACJs were supposed to come with the -ULR modifications standard; so it raises the question if Airbus is even offering that anymore, or did they decide to offer standard A359s as ACJs after the decision was made to bring the standard to 280T capability.
Seem odd that they'd go through a certification program, but then just end it after 7 aircraft, if that's indeed what happened.