February/March: A bunch of devs laid off, including Joseki, one of the lead designers. March/April: All the remaining code devs leave. June: the community manager leaves, and is "replaced" by stormshade, a Bandai Namco employee who only occasionally manages to do something that vaguely resembles competent. At this point, CPG engagement with the community literally drops to zero. No tech support, none of the regular "Top 50 S Rank" announcements, none of the regular Boss Battle announcements. Note that on the usual schedule, another expansion would have been out by this time.
About a month later, it's confirmed that the servers will be up indefinitely, and "more content" is planned for the fourth quarter. This isn't made as a general announcement; it's via Meltdown Town's podcast, which is cool, but means we still basically haven't seen a CPG employee.
A couple of weeks ago, the servers were so inconsistent that most matches ended in snags. Last Monday or so, the servers were bad enough Adam Thomas / SonOfMakuta wasn't sure he'd be able to stream. Want to guess how much communication there's been from CPG about this?
And completely unrelated to infrastructure, reverting rotation basically blew game balance to hell. Khanuum Ka was designed in a world where Rae was unplayable in ranked. When Rae returned to ranked, Fault Vet basically gained a tool for unstoppable value at 6 mana. Against Vaath or Zir'An, it's an "I win" combo on 7 mana (Fault+Rae -> Khanuum Ka).
That might not be a problem, except, well, the game has... one? Maybe? Designer left on board. No balance patches, no new content. The only saving grace is that since Duelyst doesn't have as huge a playerbase as Hearthstone or Magic, metas aren't set in stone as quickly.
Oh, and Glauber "unseven" Kotaki, the lead artist for Duelyst, is looking for work.
And no new employees for Duelyst have been announced. It's far more likely that CPG is at this point essentially axing development of Duelyst in favour of Project Aperion, their other project in development (for which they have recently hired several new devs).
People have been saying Duelyst is dying for ages, and normally I'd agree with you and say sure, it's not dying, it's just a niche game that was never going to be hugely popular. It's losing a bit too much blood for me to say that in good faith now, though.