It's a shot across the bow, to achieve a chilling effect. They've achieved a few weeks of downtime, for now, and sent a message to the project that they're being watched. It might well not be the end of hostilities.
I think you may be right about the fight not being over, I don't think they actually achieved any downtime. Youtube-dl didn't stop working for me while the takedown was in effect, and was even updated during that period.
In terms of usage, yes. In terms of development, we'll have to see. I am an optimist, but I have to recognise that good devs tend to skew away from opensource projects that are in lawyers' crosshairs, because they bring more trouble than fame.
