Honestly, this article simplifies and misleads about what was going on. The devs wanted to give everyone a little fun, but there was no real end event, just a giant party.
It's not like any of this was something new. They basically let it be Halloween, Christmas, and the end of the world all rolled into one for the past month or so. Lupines, zombie spawns, yetis in special Christmas missions, snowball fighting, santa-inspired outfits, etc.
The dark skies, red skies with eyes, and ash and snow were all remnants of previous events and would cycle through the day. Sometimes it would be pitch dark (Halloween), sometimes normal greenish tinted sky, sometimes a bright blue sky (the end day was all bright and blue sky), sometimes it would snow, other times the snow would turn red, other times it was that black sky with black snow/ask falling down, other times the sky would turn red and sometimes have those creepy eyes in it.
However, they did a good job with what they had. For the last couple of days, they leveled everyone to 50 and gave us all 4 billion info to level stuff and buy things with, added super rare and awesome loot to normal vendors, then leveled us to 69 the day before shutdown, and finally, to level 99 on the final day.
My guild and I spent time taking down an agent now that we were 99, we took on some challenges in small teams that were formerly only doable by very large numbers, and just basically had a great time experiencing some things we never did before. Even though it wasn't a new event, it was fun and memorable and people like Walrus and Dracomet did a very good job with what they had at their disposal.