A ten-year fund life cannot hold a multi-century instrument. The structures that can are the ones organized around perpetual trusts — and there are not many of them.
Each stop is a page in the graph. The order is an argument — but every one of them is also a door into the rest of it, so you can leave the path wherever it stops being useful.
The collateral is not a company, a portfolio or a reserve. It is a protocol-level claim on the settlement of an entire network — which is the first instrument in a long time whose duration actually matches the thing it is funding.