Inb4 all the credit card / PayPal scams.
What I see is that now instead of an army of botters, there will be an army of Paypal / CC fraudsters, who will buy bonds with stolen PP accounts / CC-s, sell the bonds on GE and then sell the GP to a third party.
The actual owner of the PP / CC will soon make a chargeback, Jagex will lose money. Will they remove the fraud-related bond from the game? I doubt it, because by then its already in the hands of a legit player. Will they roll back the gold that was obtained through this method? I doubt it, because by then it will be very hard to trace and again it will probably be in the hands of legit players.
In this way Jagex has created an excellent platform for money laundering, while illegit or "empty" GP will still be injected into the economy, causing inflation. This "army of botters" can easily adapt to this new method. Of course, there will be less people doing this method, because it is more illegal.