The assets that back Bitcoin
...are the present and expected real goods you can purchase with it. Just like other fiat currencies.
But perhaps you are thinking of the junk mortgage derivatives, unregulated and not backed? Bitcoin doesn't change people's ability to make and trade - or regulate - derivatives markets, any more than if they were denominated in $. However it would starve banks of the cash of savers, who win under deflation simply by holding onto "cash" in their digital wallets. Potentially it could eliminate the concepts "fractional reserve" and "a run on the bank" and thus "too big to fail". Banks would lose their ability to nationalize risk via government guarantees. They would be forced to become more conservative. So the effect here would be good too.