Music can be obtained from torrents, purchasing online or it can be obtained from legal streaming services. These are all valid if not legal sources of music. If one or more becomes too expensive or unavailable, the others will fill in the gap. This was quite visible when the music industry refused to embrace mp3 music distribution. The illegal sources flourished during this time. Once Apple, Amazon and other started selling mp3's without DRM, these illegal sources became less attractive. Note that all channels still exist but the usage will change as the pricing (risk vs. $'s) shifts between them.
Causing the streaming services to go offline will only cause customers to go to the other channels and I do not believe there will be an appreciable increase to the mp3 sales channel.