no, there aren't any such plans. There are multiple reasons, but the most important reason is that charging for the service adds responsibility and duties which I can't offer. If you pay for a service you have a right (legally and/or morally) to have certain expectations. With my available resources (both in terms of money and time) I will probably not be able to meet these expectations.
Apart of the fact that db4free.net will remain a testing service, and with a testing service there is always a possibility that something goes wrong, so data may get lost unintentionally. If you paid for the service and I lose your data, you may consider suing me. If however I offer db4free.net as is and without any guarantees (as I do), I'm pretty safe.
So I believe the current model probably works best
. If you have a need for a reliable database provider which can guarantee for your data safety or also for a minimum amount of availability, a commercial provider is certainly the better choice.