That's a really interesting idea, and one I'm definitely interested in given the pitch! I'm not sure if something like this has been attempted before so I don't really have a point of reference for this beyond the Tale of Two Towns event I spoke of in my post and the experience I've had with TTRPGs in general the past couple years.
The two things I imagine being the biggest hurdles are a consistent playerbase and keeping things fresh enough, especially for the timeframe you've laid out, which all have a couple specific things I'd keep in mind.
Lowballing the month speed at 2 sessions per game month, that's 24 sessions per game year. If there is one session a week, that is 6 real life months per year! That's a serious time investment.
In ToTT, a month lasted about a 6 hour session if I remember correctly, so 3 months to get through a year, and even then there was some dropout, especially during winter when players didn't have as much to do.
And there is of course the concern of having things to consistently do, especially if people decide to fill specific roles or if it is mandated by the server. During the early game, that is no problem, people are busy trying to survive and constantly have things to do. Mid-game, things like pottery become far less important as people generally start focusing on building and getting through the metal ages, and by late game there is usually only exploring, building projects and projects that take a long time like animal domestication left.
A lot of servers seem to get around this by having some mix of server restarts, player-driven activities like roleplay, conflict and player-made events and server events. If this is a more focused DnD style roleplay adventure I am sure things could stay fresh for longer, but that would rely on you to somewhat regularly create new things in the limited confines of VS!
All that to say that I still think it'd be worth it and a really fun experience, but a more limited runtime would probably be more realistic.
And on top of that, unless we had considerable luck and got 15 other people who had no scheduling mishaps and didn't lose interest, there would have to be a way to get people in to the game to replace those who left, something other VS servers seem to survive simply by merit of not needing a specific number of players to work and simply run with whatever player numbers they get.