Actually .onion prostitution services exist already and have for a long time. There was at least one that was very popular around 5 years ago, but I don't remember the name.

But you are absolutely right, this is pushing sex workers further underground and therefore making their lives more dangerous.

And now you'll have the "innocent" john sorting through ads selling any number of illegal offerings, because he will have to use the TOR version now.

Can't help but think this will be a boon for those in the business of sex trafficking.

Would it be surprising to say that trading in this might include Bitcoin?

It would: Monero is the de facto standard currency in the deep web nowadays, not bitcoin.

About as surprising as noticing that e.g. moving some trade to Switzerland involves increased use of Swiss franc.

I'd imagine they would use Monero or Zcash nowadays since those are proven fairly more anonymized. Bitcoin is wholly public so all it takes is one identifiable wallet to start profiling addresses they interact with.

You used to be able to tumble the bitcoins but cant realistically do it anymore due to high fees.

By Bitcoin I meant Blockchain based money.

Then you should say that or “cryptocurrency”

That I agree. But I couldn't edit it later on.

Unless they send you suitcase with human being and they don't expect them to get back with cash, then yes, it would be surprising.