I personally would suggest that its simply Spotify that might be a reason as to any shift in file sharing patterns, although I don't agree this is a valid set of statistics, its more likely that traditional but often unnoticed forms of sharing such as USB stick sharing and groups of folks converging to a friends house for a "LAN Party" are on the increase, also the rise of dark nets that allow for anonymous sharing of files and zero monitoring ability are likely to give the impression of a cessation of copyright infringement but the reality is it will continue as its based on a global reaction to an immoral and corrupt overlong monopoly that steals from artists and the consumer, when vested corporate interests stop buying political influence and giving out fat brown envelopes to buy laws then the common folks may well back down also but I don't see that happening while so much is made by so many for so few.
* GhostShip tips hat to Winston Churchill