There are some other problems that could be done to help bring people back to the game. For example, while the remaining dragons wait for the ARoP, the ARoP doesn't mean anything for those who play a biped. Lairs for dragons don't mean anything for bipeds.
If you play a dragon, then of course these are key elements that have been lacking for far too long, but to do nothing for the non-dragons, and have no plans that make the game more interesting for ALL players is what has killed things for many people.
Roleplayers want a purpose, and Horizons had the focus of being more for roleplayers back in the early days, and it's what made things fun, bugs aside.
The WA has no organization, they don't push. They don't claim land, hold it, then expand their influence until the living races push them back. The WA is all but gone since the shard merge, unless you are very high level.
The Blight Anchors were very cool initially, but wern't used to expand the WA influence the way they should have in my opinion. There is no fight to push back the blight.
I remember way back pre-release there was talk about AI, and how when a more powerful undead mob would spawn, it would initially create lesser undead, and build forces that would eventually attack towns. That whole idea went away. Attacks on towns besides the Avatar of Pain were generally few and far between. The idea that the players help to change the game world went away when mobs would just respawn in the same place over and over.
To fix the problem:
Make it so blight anchors move out from already blighted areas, then stay as they spawn mobs. After the land has stayed blighted for a certain period of time, it STAYS blighted. If all undead are removed from an area and are gone for tripple the time it was blighted, the blight fades.
Bring in quests where low level characters are treated as low levels in the fight. They are to help eliminate the undead in the smaller blighted areas(which have lower level mobs), and to act as messengers or to deliver supplies. Each quest should do something helpful, like finishing a delivery would provide a boost to those fighting on the front lines in the fight.
Other ideas might be to wipe the world and start fresh with things ballanced based on the current number of players. The game world has a TON of plots now, but there are so few people playing, those plots are useless. Worse than useless because they remind people of a time when plots were in short supply.
Tulga could push internally to make a "Horizons 2.0", a follow-up game that has all the issues fixed, but would be sold to the public as a new game. If a game is perceived as a failed game, it's harder to get new people than if a game is sold to the public as a new game. Make the new game COMPLETE, focus on depth of storyline that can be found in game without a lot of un-related quests to provide the details. Sub-plots can be found through the smaller quests, but the main quest shouldn't be impossible for the players to learn about without going to a web page.
And finally, we need communication on the OFFICIAL communication areas, these being the FORUMS and web page. IRC is nice for the developers to chat with players, but should not be the place you MUST go if you ever want information from the company that makes the product. I hate even seeing mention of the IRC channel on the forums because I don't have the time during the day to sit there in the hopes that a dev might say something.
I hope that I havn't offended anyone, but with the focus on the dragons, I think Tulga/AE has taken their eye off the larger problem of there being nothing to do. After the dragons become ancient, what will they do with their new power/abilities? The same goes for the level 120 cap, or new items, weapons, loot drops, etc. All those things go to feed the grind, but still don't give a sense of purpose.