Yes this is a critical point, you have picked up. We want to be able to accept data based on strict metadata checks (not hashes alone in some cases, but not so bad if sha3 or hmac etc.). Anyway I digress (as always).
The important point is being able to provide/get data from anywhere and the network to be able to accept it as valid and having been previously audited for inclusion on the network.
So the chains should be very small and as the network grows, become smaller (checkpoints can be taken) so very efficient. Then with genesis block known, networks can be identified, which leads to some really interesting things.
Imagine network for X type data that require Y privileges, or private/uni/health networks that can speak to public networks etc. It does open up a wealth of possibilities. In the future inter-network communications and agreements can be made, thereby taking this tech much further with specialisations possible. So Tesla cars have a network and can speak to highway controls or something (no passwords etc. to lose, no data leaks etc.), or even better hospitals and researchers securely sharing data and analysis etc.
I add this as a probing question, perhaps not having SAFE do absolutely everything for all situations makes sense, but the underlying protocols can allow a much larger even more decentralised (tree’s of tree’s chains).
We are not working on that though, but it can be interesting to look at these possibilities for the future.