I might be wrong but I don't believe that sunsetting involves staff creating a meaningful plot for your character's exit. It's simply them allowing your character to ride off into the sunset. Retiring.
Staff may be convinced to to more but the only bit one can really expect is them providing a somewhat believable exit from the city then killing your character off screen with the understanding that the official IC lore is that they are still alive somewhere sipping drinks and enjoying their retirement.
In my personal experience, you can let staff know that you're done with your PC and want to reroll and offer your PC up to be a casualty of plot at any time during your character's life. Staff can't always accommodate this and the death of your character may or may not be as meaningful as one would like but I have seen staff accommodate such requests fairly often and almost always before the character's five year mark.
Of course, I can't speak for staff. I may be misunderstanding things or things may have changed. Regardless, should any player feel like they are done with their character and aren't worried about them riding off into the sunset and living on elsewhere, I think it's fine for them to check in with staff and be like, "Yo! Bob Robert is done. I am going to make a new PC. If you guys wanted to have him killed off in some plot, I'd be very down with that." See what they say.
They may not only be able to offer a tiny bit of simple plot right then or you may have to wait longer than you want until they are ready or they may simply tell you no. Couldn't hurt to offer though!
