Then don't prune the OP_RETURN data. We could extend the mini-blockchain scheme to support key/value storage. The paradigm would be: "Just keep the final states. Forget about the old states." Do we really need to keep all history data in the blockchain? Is that "slim"? I don't think so. If we prune all old status updates we will free up 99% of the obsolete data in the blockchain and give room for the relevant data. So we're reducing the footprint of the wallet, making it more compact and more efficent. That would be "slim"!