(Bitcoin can be converted to Monero, and the bitcoin can be mixed, so it's still quite hard to do what you're suggesting: to track down the perpetrators of large-scale crimes such as this. The flipside is that criminals' opsec tends to be very poor; good police work is usually enough to capture them.)
Obviously, ospec can still blow your cover. But Monero and other assets are certainly a game changer in this space.
The recent $4.5M ransom was evidence that this isn't really theoretical: https://www.reuters.com/article/idUSKCN24W25W
(Bitcoin can be converted to Monero, and the bitcoin can be mixed, so it's still quite hard to do what you're suggesting: to track down the perpetrators of large-scale crimes such as this. The flipside is that criminals' opsec tends to be very poor; good police work is usually enough to capture them.)