There are several parallel aspects of the game that have shaped the recommendations I'm about to present. I'll first present the aspects relevant to what I'd like to present, and then get into the actual recommendation I want to make.
Alternatively, if you want you can skip past everything for a tl'dr when you get to the "Method," section.
Consideration 1: Power disparity between new players and veteran players is intentionally absolutely ridiculous. Characters who have been around for 2.5+ years are at their maximum capacity for growth, and have had potentially even more time to shape their reputation, gather power, and ingrain themselves into the story of the game. Part of why new Player Characters suck so bad is so it feels amazing when years down the line your plans hash out and actually become a badass. It's part of the design of the game.
Consideration 2: There seem to be a really good deal of Players who have had the same Player Characters for waaaaaaayyy more than 2.5 years. I'm talking like since this whole thing started in 1999 or whatever. People who have had the same character for 4-8 years or more, or even people who have had multiple characters who have each went on for 2+ years or more before they were terminated by their players. Also, generally it's these players who have stuck around with the game over all these years who are most likely to donate and support the development of this project.
Consideration 3: You can only have one character at a time. Yes, this helps ensure that the RP and story experience is not compromised by players who meta as multiple characters at the same time and break lots of rules that way. But this also means that those veterans who have stuck with their same character for 5+ years are not able to try something new on SINDOME without giving up a character they have put lots of time and emotional investment into. This is an unfortunate necessity of the game.
Recommendation: Give Veteran players a little bit more room for mechanical growth. The purpose behind this is to encourage more story engagement from Veteran players who have already got all of their UE over 2.5 years. While there is plenty of room for growth via in-character means such as accumulating power, earning reputation, and getting into better socioeconomic spheres within the Dome, some additional mechanical (specifically UE) growth opportunities can act as an engaging consolation prize to those Veteran players who have a long-running character they don't want to give up just yet, but still kind of want to try something new.
The benefits to additional UE growth for Veteran players is the previously stated increased potential for story engagement, as well as increased potential for support from those Veteran players to help SINDOME continue to live and grow. The downsides to this are an even greater disparity between new and veteran players. But that's fine. It's already part of the game design, so like whatever, you know? The devs have done a pretty good amount of work towards retaining new players, so that's fine.
tl;dr
Method: Introduce a system where a player gets to choose 1-2 stats and 3-5 skills to be "Tagged," for their character's growth. A player character continues to gain a certain amount of UE after the 2.5 year mark, however they may only apply this UE to the character's "Tagged" stats and skills. The rate at which this "Veteran UE," is gained can be easily fine-tuned by the admins and game-devs, and can be capped at whatever value they want. Heck, it could be slowed down to something REALLY slow like 1UE every 3 days or whatever. But the point is it's a value that can be easily adjusted as the admins and game-devs see fit, to to accommodate the experience they want for the players.
Even if this kind of thing has been suggested TONS of times in the past, and there's ZERO chance of this kind of thing ever happening, I'd really love to hear everyone's thoughts on this proposal.