Feral Heart

The reason why FH was really popular back in the day is because MMORPGs where you play as a animal in a simple environment was still a new thing. Now with the multiple IT servers, Cereal Soup, and many other games in the works it isn't much of a unique idea in general today. All those other games already have new models, markings, and/or a PvP system ether in the game already or being implemented later on.
The only thing that could make FH more popular again is to bring something new to the table. It's true that the source code is gone and has been gone for 7 years, but honestly I think that excuse is overdone and it seems like it's only used to shut people up. (No offense Azura)

What can we do without much of the source code, though? By the looks of it, all we can do is change textures, add new meshes, and replace maps. The only changes made after KovuLKD left the scene was removing general and replacing the original maps with what we have today. There also has been HD remasters first by Slycan (Feralrealistic or whatever it was called), FH+ by Simba/TLK4evr, and more recently by Brokami but it has been pretty hard to find without third-party sharing at this point. The reason why these upgrades are now semi to completely hidden from the public isn't relevant to say currently. Lets just say that the staff's idea of requesting content from creators not on the staff team is relatively new.

What can we do to make FH more enjoyable for new players, regardless of the source code? The biggest thing to set apart you game from the others is a plotline. FH veterans correct me if I'm wrong, but I believe FH was originally going to have a plotline that had something to do with animals on the run from civilization (hence the name "Feral" "Heart"). Kovu was going to implement a story mode with NPCs into the game. But now with him gone, that idea was nothing but a pipe dream. It's been 7-8 years now. It's a sad truth, but unless the game is rewritten all we can do is make the game more pretty. Unfortunately there isn't many people in this community like KovuLKD that is willing to write a new game.
The original Bonfire Island was a hubworld where you can socialize with your fellow players and was going to have an actual bonfire like in IT. That idea backfired due to the difficulty in actually getting into the game as hundreds of other people tried to as well. That was why Lonely Cave was created.

TL;DR: The game is outdated and slipping out of relevancy. The simplest way to set it apart is a plotline. The developer left the game and realistically we can't get anything far without him. Unless the game gets completely recreated, all we can do is add more meshes, maps, textures, and markings like we have been.

Everything WolfQueen said.

The new "badass" FH 

Yeah this would be pretty cool. Making a game that is expected to hold up to FH's "standard" would be a bit difficult, especially if you wish to add new components into the game. That is if you don't plan on using Kovu's source code. Regardless I think it's a great idea!

If a group can maintain at least two large role-plays a week, i'd say it's pretty active.

I think checking out the game in thirty/forty years would be really interesting and hilarious

Currently running out of reasons to keep playing though