I have thought a little more about the aforementioned YouTube channel and the more I think about the more I would like to do it. At the very least it would get me a little more familiar with video editing and perhaps exploring software and camera choices. If I decided to go through with it what would people find interesting to watch?
Great idea! I was having fantasies about a film about a game of Warmaster commented by two sports commentators while the game was going on. Most important would be the fun aspect, not too much mingling with detail rules but with the overall flow of the battle. I think it would be best to make a kind of public relation movie out of it which makes other gamers curious.
But back to topic:
Here in Austria in the golden age we had about 12-16 active players and some still find their way back to WM from time to time.
We are lucky to have a Tabletop Gaming Club the WoW/Keepers with regular Club Evenings where we can show our games and attract new gamers. So sometimes gamers lose their interest in WM but others step in again.
At the moment I'd say I have 4 other players I could challenge any time in the area around Vienna and another 2-3 if I'm willing to drive 1,5h to Styria. For a tournament there might be another 4-6 players I could activate at best, but that depends upon the tournament. I organised a silly "Vice Versa Tournament" a few weeks ago where players brought their own armylists and armies but played with the opponent's army (Winner was who won the most games against his own army). It was really fun but only attracted four players!
Most WM players around here also have interest in other Specialist Games or in alternative Games, some even find their way into the odd Warhammer Fantasy or 40k again

, some even totally drop out of Tabletops. It's a steady coming and going.
Imo in the golden age the most devastating thing was the onkeeping rumours about GW dropping Warmaster. A lot of players stopped playing WM or did not have a go because of those rumours (and if it's true some GW employees at the shops around here were a bit responsible for that too). As it seems GW did'nt kill WM exactly but does'nt really keep it alive either (there's a saying here: too much to die not enough to live). And although there are positive side-effects too I miss the impulse of new official rules, official army lists, new official units. Because those were the times old players would have a skeptical look and new players were drawn into the game with excitement.
On the other hand there are tapletop games which did not change for centuries and still are played...
For me Warmaster still is the best Big Battle Tabletop game I know, although I also have a game of Mortheim or Blood Bowl too.