I don't really see a problem. Historically, Friday was the prime gaming night, followed by Sunday, but as we've grown older, the online time has also reduced so there is perhaps a window of only an hour or so that you'll have large participation. The chances of a lot of people being online at any other time is much smaller. Even last Friday, when a few were on, not all had the game so we'd splintered, as was inevitable to a few on Bat 44 and a few on PUBG.
I've been one of the prime promoters of Battalion, and will continue to do so. I'm not concerned yet with participation. It's early days, and having seen so many games fall by the wayside, I'd much prefer something to be a slow burner that grows on people rather than it's played once now, thought of as flawed and so dies a death. Gameplay has some issues, and will be more attractive to some than others. Connectivity was initially flakey. Perhaps significantly there are very few maps. But then to buy into Battalion at current early access is also cheap.
What is immediately noticeable, is that if we do get a few people online, playing Battalion, our Teamspeak banter returns to some of our older merciless chaose, rather than the disciplined approach needed for PUBG. That for me is the real benefit of this style of game, and why, when I'm choosing to be online, Battalion is likely to be my game of choice.