We are still light years away from the thousands of players per instance. Also Ark supports 120 players which is a survival game so not sure how getting to 60 players moves them out of that game style. I still feel that the game is 10 years away from being released.
Long post. Most sentient part is in first paragraph below. Yes, Vav is a geek.
Maybe I can explain. What CIG is doing right now has nothing to do with how many players the PTU will support. But it does have a bearing on the total cost and the architecture they ultimately implement. For example, in 2.6.3, the game barely supports something like 30 users - so if you know how much AWS charges for your server model and network throughput for each user, you can do the math to figure out how much it will cost to support 1000 users, or a million users. It's almost linear. What CIG is doing by working on the network efficiency, is basically lowering their costs to provide the optimum user experience. If they can support 60 users per server, their costs will be something like half of what they would be with 30 users per server. If they can eek another 40 users out of that, then less than 1/3 the cost.
What they need to do in order to provide MMO capability is actually pretty interesting, but almost totally unrelated to their current work. As I see it there are a few options here, using Shard or Realm technology. This is a way of combining multiple game servers (software instances) so that the entire game (the PTU) is modeled in 1 Shard or Realm - but the Shard might be hundreds or thousands of servers combined. Each of the servers manages an area of the universe, or a set of object types, or a number of users (depending on the architecture used). Each of the servers is connected via a communications backplane, which provides updates to all the servers almost simultaneously. This backplane is a service that comes with AWS, so CIG does not need to worry about this. You can also operate multiple shards if you want, or keep growing the servers for a single shard - depending on your application architecture.
In Shard technology though, there are questions about what to do if one of the servers gets overloaded - and basically 3 ways of managing it.
1. Manage player density (Prevent users from entering overloaded game areas)
2. Manage the server frame rate (Eve Online)
3. Manage the space that each server manages, and spin up new servers where the system is overloaded.
Some MMO's use a combination of the first two. Both of these models were invented in the early 2000's, and haven't really been updated for optimizing cloud based games. The third model is enabled by modern cloud based technology, but is quite new.