Approximately 100 people have been laid off from ArenaNet as a part of the merger with NCSoft west and seniority apparently didn't affect the choices here. Many long-time employees, such as Gaile Gray, are no longer with the company.
ArenaNet's mass layoffs have kicked in and the aftermath is slowly showing up. It seems like the studio will be losing some extremely valuable people, but there is no confirmation on how many of them left the company willingly so far. By leaving willingly, we mean those who volunteered to fill some of those spots instead of just everyone being laid off forcibly.
Some of the names are popular developers, known very well among the Guild Wars 2 community, such as Benjamin Arnold. Fans nicknamed him "Fractal Ben" due to his immense work on Fractals. In case you don't happen to be a Guild Wars 2 player, Fractals are a type of instance that serve as a variation of tiered dungeons, for the lack of better words. A proper explanation would require an entire to explain.
Some others were known for their work long before Guild Wars 2 was even conceived. Gaile Gray is a legendary community coordinator, known well among Guild Wars and Guild Wars 2 player bases alike. Her appearances in the original game were often followed by her companion, The Frog, who would speak on occasion.
It was often speculated that it was Gaile Gray herself controlling him, but she denied this more than once, even though fans confirmed she could write in the same gold letters The Frog would normally speak in. She has been with the company for 18 years before splitting ways.
Josh Foreman, the person behind some of the more complex Jumping Puzzles on the whole situation during a livestream, stating that Guild Wars 2 will likely do well as these departures will keep the team focused on future content.
Meanwhile, Guild Wars fans are to figure out whether Stephen Clarke-Willson and Bill Freist remain on the team as it was them bringing the only updates to the first game. Their LinkedIn profiles still list them as working for ArenaNet, but it is not excluded that they simply didn't update them yet.