The limitation of two years for blob storage on Sui is primarily due to the variability in the cost of WAL and storage over time. Setting a fixed price for storage into the far future can be challenging, hence the arbitrary limit of two years has been set at present. However, it is possible to extend the lifetime of a blob beyond the current storage period. Walrus offers the functionality to renew storage through corresponding Blob objects on Sui. This allows wrapping these objects in shared objects with additional functions, enabling anyone to fund the long-term storage and extend the lifetime. So, you do not need to delete your existing storage to extend its availability. You just interact with the smart contract using the specific blob ID and pay the necessary storage fees without having to transmit any additional data.