The easiest part to dismantle is the part about the "lots of bands struggling to make money".
I am a semi professionnal musician, and as such i also know a lot of "bands struggling to make money" guys. There are already a plenty. Maybe 99,50 % of the musicians are struggling to make money, and it has been like that since a very long time.
And guess what, some of them make it and succesfully make a living out of it, and NONE of them depend on royalties to do so, because technically when you're a struggling musician you make approximately 90% of your income on gigs and 10% on publishing your music. And i'm being generous here. Much more often, and it has been like that since the beginning of indie production, bands invest money into producing their CD, and they never make a net income on it. Except it's still interresting to do it, for the promotion of the band. On the last year, with my band, we made approximately 25.000 € on gigs, and a whopping 800 € on vinyl/Cd releases.
The consequence of that is that musicians that make a substantial income in royalties doesn't need them to live/survive because when you're up to that point you also earn way enough money to survive with your live performances.
A lots of recent studies shows that people are definately not buying less music than before, and on the other hand getting it for free has never been so easy. Also the www and P2P has been fantastic opportunities to musicians insofar, to promote themselves and sell/give away their music, and hence get a much bigger audience than they had before, without needing to go through the very tight and controlled channel of major record companies.
You see a potential decrease in quality ? As a musican i see a very net increase. Making music and broadcasting it has never been so easy.
The movies industry is a different matter. Production prices are way higher, and potentially you could see it be much more impacted by the P2P sharing. For a simple reason : Movie makers need their movie industry. Musicians don't, at least they don't need it for broadcasting and producing anymore.