The $5b bitcoin recovery recently had the same problem.
Even if you converted 650m to cash it will be hard to move that around as well. At large numbers it is easy to flag for LEO in the economy crypto or traditional.
This kind of theft requires a mindshift change to be really successful, instead of thinking as 650m the hacker should think as few hundred thousands in annual income forever.
The amount you can safely move will increase as the market volume increases.
There are essentially two camps. The one side says:
- You can sell for cash, use mixers, NFT sales, $other_sophisitacted_technology and get away with it
The other side argues:
- You won't be able to ever cash out this sum and law enforcement will use sophisticated data mining on the blockchain and will eventually bust you
I think in reality it is like any illicit asset worth $650 Mio. It's gonna be extremely hard to launder but not impossible.