Set up all the Wurm Online servers as vanilla/unmodded Wurm Unlimited servers. Prefix/name them as "Official CodeClub - [server name] [info/description]", or put some logo at the front of them so they can be found easily, or just special-case them into the sort algorithm so they always appear top of the list. By the way, make it possible to put more than a simple one-line ellipsized server title in the launcher so players can read what a server's even about, and server owners can actually tell them without forcing them to open a web browser and type in a URL that may or may not actually completely fit in the ellipsized server title to begin with. Premium functionality already exists as leftover code in the Wurm Unlimited codebase AND in-game UI (I've always wondered about that) so this should be easy to either implement as-is or to bridge the necessary gaps to do so. Make premium an "Official CodeClub"-only feature.
Rebrand, rename, and refactor Wurm Unlimited to just "Wurm" and keep the pricetag it currently has. Existing Wurm Online players who have a certain amount of time spent premium on their accounts and have been active in the last XX days/months/decades/centuries get a coupon code to get the game on Steam with, or if they already own the game, to gift it to a friend.
Devote some real effort to making a real Wurm API for addon developers and server owners to work with. Save your hardest-working fans - the people who love the game so much they spend countless hours of their lives jumping through Javassist hoops and bytecode substitution to make the simplest tasks possible, all in the name of adding something fun albeit primitive-by-nature for everyone to enjoy. Let alone the agony of keeping it working from release to release, update to update. (I'm certainly not implying that developers would no longer have to keep their code working between releases, only that any programmer who's been around the codeblock knows that an actual API helps a great deal with any and all effort required.)
Setup an API database maintained by CodeClub for players, servers, and addons.
For players, account registration puts you into the API. This is a no-brainer. Many WU servers already try to associate players with their Steam accounts, whether to restrict deed creation, login to their websites, or whatever else they can think of. This would just make doing so easier. Actual gameplay is unaffected by such a system anyway.
For servers, server owners register their servers with the CCAPIDB to have it show up in the launcher. If you don't want it in the launcher, register it but set it hidden. This makes management, advertisement, validation, and potentially even updates to new releases easier to manage. Additionally, character creation databases can exist both CC-side and server-side, and servers can choose between one of the two functionalities. Servers can decide either (a) players who want to join our server must create a fresh character from scratch and use it only on our server, or (b) players who want to join our server can use one of their "global characters" which can then access any server that allows them to. For (b), server owners can then link their borders to other servers in the CCAPIDB if they wanted to, allowing roaming freedom if server owners want to do that. Hell, the simple act of clustering then becomes a LOT easier.
For addons, addon developers register their addons with an API developer key/token system. This would make an actual up-to-date automatic list of available mods possible, would make versioning, releases, and even visibility easier, and the launcher could include the possibility to add/remove/configure them. And servers could actually authenticate modded clients this way, primarily in the interest of making server-side enforcement/restriction of client-side mods possible, and namely in the case of CodeClub's servers. If you connect to CodeClub Official, no mods are initialized client side. Also, this releases players from the absolute living hell of having to cater their mod installations to the server they want to play on that day, with no real user-friendly interface to do so. The server says "we require mods A B and C, we allow-but-not-require mods X Y and Z, and we absolutely forbid mods 1 2 and 3" and the client initializes on that basis to connect.
Last but not least, take all the Wurm Online servers offline. They now exist as "Wurm" servers, at the top of a list of all Wurm servers in existence.
The game is f*cking dead. 300 players divided across 9 servers does not an "MMO" make and thus there's an overall lack of activity no matter where you go. And whatever Unlimited communities remain, often with little longevity, suffer from content ceilings due to the absolute bullsh*t hoops that coders have to jump through to make their experience unique or more fun. It's time to modernize and revive it in a more universal and accessible way, for players, server administrators, and coders alike. Not to mention, CC's own release cycle is simplified and no longer needs to be time-staggered on account of having 1 codebase instead of 2.
Now my question. How serious is CodeClub about having a successful product?