The capacity of the NA's Siel or Israphel is 9000.
The server's page for class breakdown shows only characters which aion classic kinah have been uploaded to MyAion but not online characters and not all characters registered. The MyAion DPS Meter version is for servers with classic versions and doesn't have many characters available for upload.
The capacity of the NA's Siel or Israphel is 9000. You can also see the exact number of characters in each region (NA, RU, and JP) online when your mouse's cursor is hovered over the bar with the percentage. Other regions do not have exact numbers for online users or capacity of servers. They only share percent values. However, you can calculate capacity using the search function that is available in game. It returns up to 100 characters, which means you must split your results according to class or maybe even levels if there are a lot of players playing. The capacity was 3000 when I last updated it for EU-Stormwing server. Before KR switched to sharing percentage values, they had set the capacity at 12000 for Israphel, Nazekan and 10000 for Zikel, Vaziel. Three more classic KR servers were added already when they were hiding exact numbers as well as capacity.
Don't forget that EU has lower server capacity. Stormwing's capacity was 3000 last time I calculated it. However, Aion was in EU always had the largest population So Classic is expected to bring even more people into EU.
I'd say it'll take about 3-6 months for the excitement to go down and for the majority of fans who are a bit grumpy to get done with the current gear/content grind. Judging by the peak players chart shown in the second remarks here, the number of players are steadily decreasing.
Add on question how is the balance between factions? Thinking of doing an elyos siel, as back in the days it was played like an asmo. However, wondering what are the major advantages to doing so. I'm playing on Aussie internet, which means I am not too much pvp-focused. I'm just looking to test my chanter as well as pve/overworld.
It is unclear how long, but the group of players who intend on sticking with the game has already made it through the initial phase of leveling, so there won't be a lot of players in the initial areas , aside from getting rifted. Anyone who reaches 42 is sure to stick.
as someone who has played aion before and after I'm glad to say that the game is excellent however, it is backed by a corporation who is way too shrewd to play the game for its own sake. Classic is having a shaky launch due to ncsoft forcing players to sign up for a subscription base. It also introduced microtransactions and p2w-related elements that are in the game. Most f2p games don’t attempt to do either, so ncsoft evidently wants to earn the maximum amount of money from the players before the buy aion classic kinah eu excitement fades. If anything, private server aion is better at the moment.