All we can really do is follow the current trend. We don't know what Sony's goals are for the project because they haven't told us. We can make informed ideas about it, which would be to be above a certain threshold, though that number is high guess work.
We can look at other, possibly, similar projects to see what their expectations were. Such as Anthem where it failed to meet EA's sales expectations, and though that didn't outright kill the game, it certainly deprioritized it and put it on watch, with Anthem 2.0 being the hail Mary attempted at resuscitating it.
I have strong doubts that Marathon performing today the same as Hunt is what Sony would like to see. I'm going to guess that Marathon cost the same/similar/more than Arc, and much more than Hunt did, certainly by launch.
What I'd like to be is informed of the state of Marathon in 2026 as it exists in the realm of GaaS such that when we get news about it from Sony/Bungie we can feel like we understand more about what that news is.
It also gives us the chance to question when news isn't delivered. Such as why has there been now press release about number of copies sold? or the usual other metrics scooped up and dumped out by marketing. Best we got was the NPC kill tracker which under performed based on their own metrics. And if that was a bullshit number, then I question why Bungie didn't decide to bullshit it in other direction, award a 10:1 kill ratio to make the game seem like a massive success? I'm going to assume the number was real and Bungie were being honest about their failure to hit targets.