Something must have changed, otherwise there would still be 700 people on arena
Yes, something has changed: The 700 have grown older. About 85 can be found in
https://bearcats18.enjin.com/rip, maybe some more can be found in
http://bbs.hitechcreations.com/smf/index.php/topic,392760.0.html. There's over 100 names in the Finnish Squads forum members list. Some of them I've never heard of so they may have been two-weekers, some I know have only been online during Eurocon. Some have moved to another flight sim for a more historic setup. The majority of those I know have quit flying sims altogether for various real life reasons. Gone are the days when there'd be 20+ of us online on Friday nights.
The same has most likely happened everywhere. The game hasn't changed that much, the people having played it have. Yet whenever for some odd reason the bunch gets online together, the same enthusiasm can be felt. There's just so many more things to do, social media being one huge reason for people not having time to play any more.