"There's a reason we don't see many modern arena shooters - because they're just not really popular now. The industry clearly moved onto other genres a long time ago."

That is really the biggest mystery to me.
This particular genre did not have any big successes in... decades, at this point?

All games that tried to enter had rather small launch peaks and then kind of fizzled to low hundreds (if that much).

Online games without any kind of progression that are pure PvP arenas just don't do well anymore.
And those that bungle their own launches and sit at about 60% or so obviously don't stand much of a chance, relaunch or not.

Sure, it sucks for the devs, and maybe the game is even great now, who knows.
But in a market with way too many games, in a genre that hasn't been popular in a long while, you really only get one shot.