Obviously as you say, if a court doesn't recognize that bitcoin is legal property that is owned by someone, then there will be serious issues as to persecuting someone for money laundering and other crimes that are done through bitcoin, and could seriously open up loopholes for criminals.
As a result, I think that most countries will start to accept that bitcoin is legal, private property sooner or later.
We've even seen this in China where the court in Shenzhen had recently ruled that owning bitcoin is legal, as it is owning private property.
It's irrelevant. Cryptocurrencies don't depend on laws to determine ownership. They depend on math. Though I suppose it could even be helpful, as a government could not then compel you to hand over something that you don't legally possess.
I'd definitely agree with you mostly, except in the case of stolen bitcoins or whatnot, or companies running fraudulent investments that are quite common, would they be incriminated at all given if bitcoin is not recognized legally? But as you say, the transaction making and storage of bitcoin itself is secured by the blockchain, it's separate from the legal system.