It's not uncommon for a new multiplayer game to start out with gaudy player-count numbers only to taper off as time goes on. In the case of For Honor, though, its drop off was much more dramatic, in terms of speed and volume, and it might have hit rock bottom.
This is especially disappointing for For Honor, as Ubisoft only just recently rolled out a slew of changes to the balance of their game, specifically as it relates to in-game currency (Steel) and the power of purchasable gear, which were among For Honor''s biggest points of criticism.
In an aggressive PR blitz, Ubisoft increased the amount of Steel players earn from doing daily activities (matches and Orders), and they rebalanced Revenge mode, which was part of the reason why the microtransactions were so controversial.
Before For Honor rolled out these changes on March 31, the game had a daily average of 3-6 thousand players on Steam, according to Githyp. Since then, the daily average has been a solid 3-6 thousand players. This player count routinely ranks For Honor around the 80th most played PC game, behind even single-player or story-driven titles, let alone other competitive multi-player titles.
For Honor's situation isn't even replicated in other controversial Ubisoft titles. Rainbox Six: Siege, which many people have hyperbolically declared dead with familiar criticisms, is routinely in the top 20 with almost 20,000 daily players on average. Of course, it's no No Man's Sky, but For Honor isn't exactly doing great.
Many predicted, as soon as the microtransactions were fully detailed, that For Honor could go the way of Evolve, a game that barely survived similar initial controversy only to completely shut down after more than a year of limping along. With Evolve, the gaming community seemed to think that, no matter what changes were implemented, Turtle Rock Studios had already burned the bridge.
Of course, that remains to be seen with For Honor, but you would hope that these kinds of changes are intended to increase player engagement and reassure the community that they are listening to feedback and developing in response to it, but that just hasn't been the case thus far for For Honor.
We could also be at the stage where Ubisoft is just hoping to keep their core audience of dedicated followers happy, and not necessarily trying to attract new or lost players. If they are trying to grow their player count, though, I'd expect to see them follow the roadmap of other games that haven't sold well or lost players. That usually starts with a Free Weekend. Titanfall 2 has already had one of these, Dishonored 2 has a free demo up, and Evolve tried this when things were looking bad. Of course, when this didn't work for Evolve, they tried to go Free-To-Play and the rest is history.
Ubisoft, hoping to avoid the same fate, will evidently need to try something else or make further improvements to reinvigorate For Honor's once-vast audience that has been whittled down to its most hardcore group.