Minting APR is only applied to Proven SPK (service providers).
To get storage from the network you have to Power SPK, which then gives your a resource credit to keep files stored on network. There isn't a reason to have a burnable sink unless:
Network usage goes down. When this happens it means people have let contracts expire(less storage) so our ability to probe the storage ecosystem has been diminished. At this time a transaction fee(on all liquid transactions and DEX trades) is applied with the fee being burned to reattain equilibrium. This fee does not effect anybody using the token for storage, and the feedback mechanism should work to keep the price of storage reasonable.