It says "on all new worlds". I guess it depends on what they mean by "new worlds". If it's worlds to come or worlds started after a certain date (or simply all 2.X servers), idk. Still, i wouldn't be surprised if they in a month come up with something like "This worked so well, we want to implement it on all servers". It doesn't make new worlds more tempting for non-payers, and our job is to keep the server itself active so payers still have a reason to pay.