Taking megaupload takedown into consideration this scenario is IMHO not only probable, but inevitable.
This is flawed comparison. I think we can assume that 90+% of Megaupload's traffic was illegal/cracked apps/games/movies/music. If 70-90% of all bitcoin transactions involved illegal drugs/weapons, then you might have an argument.
Bitcoin {IS NOT} a Megaupload.
Of course it is not. And we are not even talking about Bitcoin, but MtGox, specifically.
But how does that matter to the US government ?
Right. MTGox {IS NOT} a Megaupload. THat's what I mean to say.
How it matters? No one is breaking any laws by transacting bitcoins using MTGox. Contrast that to uploading copyrighted material to a public server, which is by itself a direct criminal act in many countries.