There have been several posts recently about merging the servers. A lot of people seem to assume it's something that PWE can "just do" and aren't aware of the full ramifications of this.
This post is an attempt to clear things up, and de-mystify some of the actual process. (All data is based on my own research from managing multiple private servers, working with the PWE/PW-CN Development teams, and from facts provided by previous Community Managers.)
For the basics....
1. Your basic character data is stored in two SQL databases. This has the links to the relational tables for your account, guild, spouse, level, ect. 2. Your extended character data is stored in an xml format file. This has the detailed character information on level, attributes, quests, skills, gear, inventory, bank, ect. 3. Then all of this data is cross-linked within several different proprietary format databases and the main account table.
So it's not a simple matter of changing it in just one spot. You cannot just merge the data in from one database to another.
It will additionally have to be changed in each of the other databases, and in all of the cross-linked data between your account, and everyone else that you've interacted with. On top of that you've got the account/character table, which has it's own inherent limitations. (We won't go into a lot of detail on that here because it's not as relevant)
Now, which servers could merge, if they were inclined to do so?
West Coast Sanctuary Lost City (PvP) Heaven's Tear Archosaur
East Coast Dreamweaver Raging Tide Harshlands (PvP)
Now, the servers that could possibly merge are in blue. Anything in red can not be merged. (Technically it's possible that they eventually could, maybe, but it's just not realistic. For all intents and purposes, it's simply never going to happen because way too much work is involved with a very high possibility of error or failure.)
Heaven's Tear can merge with Sanctuary or Archosaur.
Archosaur can merge with Sanctuary or Heaven's Tear.
Heaven's Tear and Archosaur can merge together into Sanctuary, but that's going to be really brutal for both the hardware and events. Just merging two could be pushing it.
Now take a look at it from a hardware standpoint. You'll essentially be cutting off all the hardware from the one server, and putting double the load on the server you merge into. The largest impact on this would be the instance servers that manage things like FB/WS/TT/FC/Lunar. You'll have double or triple the people in those instances and putting that much more load on the data stream for each instance server.
Here's a basic layout..
Main world server
Boutique server (Yes, it needs it's own server now.)
Instance servers (This is mostly guesswork, but it should be similar) ______FB19 instances ______FB29, 39, and Secret Passage ______FB49(51), 59, and 69 ______The list just keeps on going, but you should get the idea by now.
Each of those servers is an individual piece of hardware with it's own processing limitations. The reason it's split up like that is to better handle the load because each "map" for each instance takes up a certain amount of RAM and CPU cycles. The more people that are in an instance, the more CPU cycles are required for it to function. By dividing the servers load across multiple hardware servers, they are able to accommodate the millions that play the game. You can run all the instances on one server with 32-64GB of RAM, but your CPU won't be able to handle more than a few thousand people playing.
Now, that's the server-side of things. As you can see, there's really no option for the PvP servers or the East Coast. Any further discussion on merging those is pretty much moot. The time and cost that would be involved in such an event far outweighs any possible benefits.
Now consider the community. All those TW factions.... If you merge the servers, they aren't going to reduce, they'll increase. You'll have twice as many factions lobbying for the land. Initially it may prove interesting. In the end though, it's going to have a pretty large negative impact on the community. You'll end up with the top tier factions from each server fighting each other and the rest of the players will just be SoL. It's practically there now, but this season has been a bit more interesting on Sanctuary than the last few. Long term, TW gets boring, people quit doing TW, those people leave to do something more interesting on another game.
Now think about West Arch. You think the number of catshops in Archosaur kills your FPS now? Imagine what it's like when you double or triple the number of catshops? No, that drop in FPS in those locations isn't an issue with load on the server. It's your CPU struggling to render everything because this is an aging title that still doesn't use your GPU for the majority of graphical processing. I don't care that you have an i7 hexacore processor with an Nvidia Titan, your FPS will still drop because of the way the client works. (been there, done that)
What about events? Imagine Smoke over Archosaur with double or triple the people participating. World bosses. Drake. The list goes on. I'm not sure about Archosaur or Heaven's Tear, but those events are bad enough on Sanctuary as it is. Arguably though, Sanctuary is the most populated server of them all though because it was the first PVE server that existed.
Initially it will appear to increase the activity on the servers, but it's not really. You're just combining the load. You aren't bringing new people into the game, and it's not going to do anything that would attract new players. Long term, it's more likely to have a negative effect on the overall player base. You can bring up the EU server merge all you want. Those servers hadn't been around for 5+ years when they were merged. It's like comparing apples to oranges.
Personally, I'd make this a sticky, but we have too many sticky threads as it is, and it isn't like anyone would bother to read it before posting yet another "Can we have a server merge?" thread.
/TLDR, It's remotely feasible that Archosaur can merge with Heaven's Tear, and that's pretty much the only thing that could happen. IF PWE was inclined to do so. Right now they aren't even inclined to provide basic support or a Community Manager. (I've got the experience, and would apply for the position; except that I'm pretty sure PWE won't pay me anywhere near what I make now, and I'm not moving to San Jose.)