I think they will continue to do well and then remain fine for a while longer on player count, but at this point I think the writing is on the wall that their time to shine has passed. Full disclosure - PS4 only player, but that said I've been wishing to try the game for many months. At this point, I have stopped caring at all and if it launched tonight I wouldn't shell out any money to buy it just because of the next couple months being stacked with options. Fortnite still holds up, RDR2 is on the horizon (different yes, but I'm convinced it will be drawing interest from all genres for a bit) and hot damn everything I've read about Duty has given me high expectations for its foray into the genre. People sometimes take this as some sort of personal attack against MS (who I think is on a better track than Sony), but whatever deal they made to keep it off PS4 to date is going to be the death of that game whether it helped propel it forward or not (which I assume it has). Just way too much time given to better equipped devs to sneak in and canalize the market while also propping up the market's expectations, and I think Duty is about to step toe to toe with Fortnite and render Pubg to tier two status.
I've pretty much played all the BR games, and honestly... None really hold up against PUBG.
Fortnite is a fun pickup game, but no matter how much they update the map, it's still the same. The tactics are really different as well.
H1Z1 really just feels outdated. It's okay, but doesn't really standout. It just doesn't do anything really well. It's kinda just passable as a BR game.
Duty looks really interesting, but the lower player count, first person only, and map I feel my make it different, but no really better than PUBG. The first person perspective only I thinks hurts it a bit, as it took no time at all before I was constantly sliding and jumping while doing 360's in order to get around. There's very little creep and stealth there.
PUBG blends the tactics and realism aspect just right. That's the bread and butter of that game. It's got the ballistics and realism that none of the others have. It helps to have perspective options as well. BR games require you to keep your eyes peeled at all times. More so than any other type of game. Third person perspective really helps with that.
I think Blackout will fit nicely between Fortnite and PUBG while not devastating either one.