I think most of the servers nowadays since FFXIV launched are averaging between 600 to 800 players on a weekday. On a weekend, many servers are averaging around 1000 to 1200 players.

On Bismarck, I've estimated that at most 77% drop in population since the server merge with Seraph in 2010 compared to 2013, post-FFXIV launch.

That's something to keep in mind.