If the RIAA goes away that doesn't mean that labels will.
But the market will be different. There will be more people with smaller pieces of the pie, rather than the way things are now, where you have 5 or 6 big players with the vast majority of it, and all the rest of thoes indie labels with their little scraps of what's left.
It won't be quite as profitable to cater to 'lowest common denominator', instead music (like many entertainment markets) will move more toward niches.
That still won't stop "casual piracy" (i.e., individuals trading music via P2P), but so what?
Almost every major study done so far (most of which have been funded by the RIAA or its Canadian equivalent even) has shown that not only does P2P file trading not hurt music sales, but because of the viral nature of increased exposure to things that consumers might not have bothered with buying, it actually has the net effect of a slight INCREASE in music sales.
And face it... if you're a small label, or a self-produced, self-financed individual or band, that kind of marketing might be the only kind you can afford (i.e., free), when you don't have the financial might of a BMG or a Sony behind your act.