I'd be lying if I said the didn't want a server with longevity. I'd love a server that has a long lifespan in mind, and executes it well. Being completely honest, the only servers to do that in recent years were Mir Chronicles & Artificial (sort of, they had a couple good years but its now mostly fishers and the odd players).
The biggest challenge is keeping players interested. In my personal opinion there are a couple major factors to take into account to make a successful longevity server.
1) The first a most important: Don't create a Discord server. If you want somewhere for discussion, the Lomcn team can open a subsection forum dedicated to your server. Discords have proven time and time again that there are a handful of influential players that will cry till hearts content till they get their own way. Influence from players via discord has, and continues to kill Mir servers quickly.
2) The server has to be released in a good standard, i.e most of, if not 95% of bugs and glitches fixed. There are too many players out there with knowledge to exploit known bugs, but also makes gameplay awful, and off-putting. (So please don't rush a server together as your post did suggest), longevity requires game developer-like experience.
3) Do not rush content. Don't rush content updates as fast as you can create them. People do tend to reach end-game rather quick nowadays, and cry for further content, but the matter of fact is that it doesn't allow the casual player(s) time to experience the current content before being made irrelevant again. That's another great point, games nowadays do need to cater for both your jobless stay at home lazy bunch, and casuals so there needs to be a way of bridging that gap. In my opinion, your casuals are the most likely to stay around longer, as the people who race to the top are generally the ones who burn out quicker.
4) Don't be influenced by community cries for change. Sure, take on board any feedback, but ultimately make decisions on any changes or amendments based on your own test and analysis of the situation, and deal with it on a case by case basis.
5) Engage with the community. Keep the community up to date with planned changes, updates or behind the scenes. Hire community managers or mods to speak up on your behalf if your time is consumed. When server owners disappear or go silent, the community lose faith.
6) I know you've already touched on this, but don't create a server with profit in mind. Sure, find a way to make a few quid to cover the necessary costs, but one thing I've found with Mir is you have a wide range of demographics which can cause disadvantages.
7) Be innovative. Don't be scared to try something new. Think outside of the box, implement completely new, and unseen idea's.
8) Test, test & test again.
9) Don't be soft on the community. If they're purposely exploiting, or cheating, ban them, no exceptions.
10) Which brings me to my last piece of input. Purpose built anti-cheat software. It's become incredibly obvious that the servers around today are not at all capable of catching or dealing with cheats. A really good anti-cheat system will go a long long way with Mir, as players are constantly trying to find a way to gain unfair advantages.
There's my 50p timer expired, so I'll just retire to the background now.