Yes and no.
Feralheart isn't dead by any means. It still has an active playerbase and there's never a time when no players are on. But, it will never reach its peak of popularity again IMO, which was probably around 2012/2013/2014? I wasn't a member before 2012, so I can't tell if it was fairly populated or not before that. But the game has definitely slowed down a bit? The community isn't AS lively and populated as it once was, and I haven't seen more than maybe 800-900 people online in-game for a long, long time.
Sure, we did break a record the day the new update was released, but that number of people hasn't been on consistently. I'm not quite sure what the average number of people online in-game is after the update so honestly most of this is just based off of what I personally have seen in-game and on the forum, but it doesn't seem to be near what it has been in the past, and the forum is fairly slow these days too. I have to mostly agree with WolfQueen here---between the hacking event, the plain lack of actual game updates (which I understand is impossible to do, but is still definitely something that turns some people away), the new game revamp (which did bring a lot of people back, but also made a lot of people leave), registration, and especially the login system, there's definitely been a decline in members. And though some of those didn't personally annoy me (like the revamp which I quite enjoy and such), it did annoy a lot of other people. And I'm not saying that things like the registration and login tab and everything were bad, but that's just what I've noticed has made a lot of players leave.
Basically, to sum up this messy ramble: Feralheart isn't dead or dying, but its not as active and lively as it once was and I don't think it ever will be unless some sort of miracle happens and Kov returns and gives frequent game updates or something. And honestly, I can't say I dislike the smaller amount of members. Much more peaceful and a lot less drama. But ehh, this is just my opinion. I just can't claim that the game hasn't seen a small decline at all---though the revamp has definitely made a lot of people come back, so hopefully with more frequent (not 'frequent' as in like every week, but at least maybe seasonal or something) updates/revamps more and more people will keep coming back to play, and Feralheart seems to be getting a bit more popular again already, so really all I can say is just that hopefully Feralheart will pick back up again in the future.