Not keen on Destiny 3: Battle Royale, but definitely keen on Bungie: Battle Royale.
Do Bungie still own the rights to Marathon? That's an option if they felt determined to slap an IP on it.
I think the ship has sailed for this trend. It's by no means a dying trend, I just feel like It's a little too late to the party at this point.
Fortnite & PUBG have been imprinted in peoples heads as definitive BR experiences, and that's not a simple thing to change. Sure we will see tons of variations of the genre, but nothing like these two.
Will anything be as successful? Possibly not.
As you say, too late to the party so the market will be diluted.
Will someone make a better game? Almost by default.
PUBG has an absolutely awful default ruleset. It would be hard for a game to be as bad at being a BR game without cribbing the basic rules directly from PUBG, as Fortnite: BR does.