I would think so - It definitely is not as popular as it was as year ago though, but is still very active. I know many forums that only get one post every hour on each section of the forums, whereas TBT gets multiple posts a minute (especially on cycle threads and retail threads). About the time I left in early February last year (I've returned now), TBT was becoming very popular for talking about things that weren't even animal crossing related. Many people were selling pokemon and nintendo codes for bell tree bells. It was also over-run by HUNDREDS of cycle threads and a gazillion newbies who got trampled by experienced players. Now, its more relaxed and whilst it still has a ton of active members, its also doesn't have that many options for acnl in game items or villagers as it used to.
As for how popular ACNL is, I'd say a lot of people don't play it anymore. I certainly thought I was done for good, but I've come back since I've missed it. Almost everyone I knew in 2014/15 is no longer playing ACNL. Whilst they may still be on the forums, many have just decided to stay around the museum area or tbt marketplace. A lot of older ACNL players (ones who started in 2013), have been selling a lot of their items and then putting down the game for good.
I also wanted to mention; there is a spike in the amount of active TBT users during holidays (June, July, August & December and January).
I don't think it's as popular, but TBT aside, I think there's some kind of boom in new players. All of a sudden, earlier last year, at least 3-4 guys at my school and then a bunch of users on this app that I frequent all began posting about it. I have no idea what happened xD
It obviously is around here, but in general? No. I think a lot of people play for a few months and then they stop because they're busy or they're bored...or maybe they find a new game to obsess over. I'm happy it's still going strong for us die hard fans!
I'm juggling five right now! Three of mine and two for my husband. I don't spend as much time playing as I used to, though. With Bunifrey complete, I mostly just log in to make sure no perma-villagers are leaving. But Balamb needs to be completely reworked and Gemedet is my new town, so that will keep me busy for a LONG time.
To stay on-topic, I don't think it's as popular as it was even a year ago but I'd say TBT is still very much active and a lot of people still play the game, especially since newbies are discovering the game still.
Not as popular as it was but I know people who stopped playing for awhile but now have just gotten back into it. I took my first ever break after 2 years of playing it straight through. that break really helped me out. I think that is part of the issue for a lot of people they become so obsessed with it that they tire themselves out to try and get everything done so they either a.stop playing completely b.reset their town or c.take a break. I find b and c more frequent then option a. I don't know too many people who just quite and never went back. As for the site its definitively still popular though I wasn't around when it was huge but this site is still very much alive.
I know that quite a few people both older players and newer ones are still going strong because both of my shops(one is for hybrids the other is for unorderable items galore) are doing pretty well. Sure there are spurts where a day or two will go by with nothing going on but for the last few days business is booming.