Martin Kerstein, Head of Global Community, posted on the official forum additional explanation about changes that will affect the world transfers.
Due to community concerns about the effect of free transfers on world versus world, starting on November 1 we are going to change how often players are allowed to transfer worlds. After the update, players will be able to transfer worlds once every 7 days instead of once every 24 hours. We are also actively working on getting the guesting functionality in place. Thank you for your understanding.