Imma be super honest: the more I think about it, the more that this CAN'T be the last pack.
Look, Frontier has, over the years, proven time and time again that they're aware of what the players want. Omitting aviaries and aquariums, they've gotten almost all of our requests, such as more monkeys, the top canids (apart from the Canis group and dholes), bringing up several underrepresented continents, and even several requested animals thay we thought were lost but ended up being squeezed somewhere else.
Now, why is it that we've had 2 packs where there were super key animals thay would've been very easy to implement yet they weren't added? There's no way Frontier doesn't know we haven't asked for the American black bear or coati and there's no way they don't know we don't want more fowl.
I bet that they still have some things in store for us, I truly think they do. I dunno how much further the devs will go, but at most I still see 2 more DLCs to be released and another anniversary. I feel like we aren't done yet