Average players have grown from 2014 to 2020 from avg players from 4,764 up to 14,816 as of now.
While there are troughs of up and downs , the over all average and max players is not that of a dead game.
I would argue that all games that are multiplayer go thru an initial slow release ( Normally ) , then hit a max player point hype ...
Then eventually either sit in a comfortable trough area or fizzle out.
The history of Arma shows a steady decrease near end of year .. and a upbeat towards the beginning and middle.
Even if Arma 3 is a dying game as your statement in the O.P. suggests , its a slow dying dragon with plenty of breathes for any servers
That wish to bring player base into there communities.
Those average stats of 14K put it in line with
16,872
18,140
Counter-Strike
16,552
19,035
Football Manager 2019
16,488
18,326
War Thunder
16,200
19,767
The Elder Scrolls V: Skyrim Special Edition
15,889
18,761
7 Days to Die
15,005
18,406
The Elder Scrolls Online
14,816
17,057
Fallout 4
14,535
18,288
Arma 3
14,078
16,669
Europa Universalis IV
14,022
19,223
NBA 2K20
13,985
17,089
Farming Simulator 19
13,833
14,810
Brawlhalla
13,650
19,748
部落与弯刀
13,450
17,506
Don't Starve Together
13,435
16,299
Conan Exiles
12,489
16,303
Left 4 Dead 2
12,244
12,788
eFootball PES 2020
12,190
12,731
Dota Underlords
12,119
15,749
Black Desert Online
11,612
12,711
Cities: Skylines
11,584
13,336
RimWorld
11,372
14,083
Age of Empires II: Definitive Edition
10,806
11,084
Spacewar
9,989
11,712
DARK SOULS™ III
9,820
14,739
FINAL FANTASY XIV Online
9,489
11,240
The Elder Scrolls V: Skyrim
9,170
11,346
Stellaris
None of which are dead games or have seen there best days.
Just food for thought , Wish you all the best ?