FairyEmpire Brad on the Bombcast spoke to the devs about this, as it is using the (now fairly old) Source engine. They said getting the map as big as it was, and getting up to 60 players, was as far as they could push it. Anecdotally they said they spent as much time getting those player counts to work, as they did on the rest of the game combined.
It made it sound like anything beyond 60 was very unlikely.
Sounds fine by me, the game is fun as is, I don't see more teams as a necessity. Given how the game focuses on teamwork far more than something like Fortnite, I've seen far more final two circles with many teams alive, still, whereas there's usually <10 players left in the last 3-4 circles over there or on PUBG. It's very fun and balanced as it is, but I was wondering if they planned to increase numbers, like Blackout did (it started with 80 I think, at one point also had like 120). Don't mind if they don't, the map could get quite hectic with twice as many players.