I am going to argue exactly this.
EDIT - LOL, I think I misread your post. I didn't see the word "non". Nevermind, everything stands.
[I do like, and rate your posts by the way, when I read them properly!].
I believe the main false emotive assumption made by UO players of a certain zealous mindset is to ignore the factually obvious,they have convinced themselves and everyone PvP is not popular.
Look at this poster below for example, I believe this guy is a troll, who keeps pumping out the same old rhetoric no matter what.
His facts are easily annihilated, I only lack the time to do it completely.
My evidence to prove PvP games are in fact the most popular games in existence right now.
Most popular 50 games right now;
The 50+ Most Popular Video Games Right Now
1. Fortnite: Battle Royale - SERIOUSLY PvP with a Feluccan style environment. This game is controversial, yet captures the essence of UO in its prime.
2. Grand Theft Auto V - Seriously a Feluccan rogue playstyle.
3. Minecraft - Kids game, UO has a lot of Minecraft similarities with its retro graphics and levels of customisation - current Castle contest fits this style perfectly.
4. Tom Clancy's Rainbow Six Siege - Pure PvP.
5. Overwatch - Team based multiplayer online first person shooter = PvP.
6. PlayerUnknown's Battlegrounds - I wonder.
7.
8. League of Legends - Multiplayer online battle arena.
9.
10.
11. Call of Duty Black Ops.
12. Call of Duty WWII.
13. Counter Strike Global Offensive.
14. Roblox - Again Kids game, so much in common with UO, like Minecraft, my kids play this, they also look over my shoulder in awe at UO which I won't let them play, don't want it to affect their studies.
15. God of War.
16. Call of Duty Black Ops III.
17. Battlefield 1.
18. Blah blah blah, I'm getting bored now.
Hopefully by this point, I have completely proved the point as to the most popular style of game = PvP without the slightest doubt, beyond any sort of reproach or argument.
You can look at any site ranking games, and you will get a similar story, I picked this one randomly.
So lets take this as read from now, anything stating anything different, is just plain and simply wrong, and can be ignored for all purposes of debate.
So, moving on, lets look at UO, and what it can do, to re-establish itself.
UO is known nostalgically for great PvP, it fits the current retro mold, it is also known for it's fast paced, and super fun style of PvP - this was a HUGE draw for UO, one which years and years of destroying it from the game have decimated UO. Bring it back, focus the game around it.