Hardcore uploaders/downloaders will start using software which blocks their IP address. There are so many occasional downloaders that the ISP won’t be able (or even want to, for financial reasons) to go after them. And if music sales are tanking, the main reason is the awful quality of what passes for popular music these days.
Exhibit A: "Flava Flav"
Anonymizing software will get you only so far. There are several remedies to stop their use on a single server, or at the isp level.
“will start using software which blocks their IP address.”
Those schemes have not been proven to work so well. Anonymous routers have been set up by the RIAA in some cases to get the IP addresses anyway.
At any rate this is the last gasp of a dying industry.
Teens will take advantage of the massive sizes of todays laptop drives, and large USB drives, and simply exchange music collections in person, bypassing the Internet entirely.