Very interesting post. Allow me to add a couple of points to your quest.
The diagram below represents our typical use case where we have a electric grid and several geographic areas with the default three layers cells.
Note:the cells are created according the number of devices they contain.The layers represent different physical electric grids connected in a redundant way.
Like the diagram is demonstrating, in theory we could just have a blockspace per smart contract. But in order to do that that we would have to build a sharding solution (Sharding divides the blockchain into smaller pieces, each of which is responsible for processing a subset of transactions. Each shard could then be dedicated to a different smart contract. This would be more efficient than having each smart contract run on its own blockchain, but it would still be more complex than simply having a shared blockspace for all smart contracts.).
Which leads to fragmentation,( Fragmentation occurs when the overall blockchain is divided into too many small pieces. This can make it difficult for transactions to be processed quickly and efficiently.) besides security,cost and privacy.
How you would do that in a secure/cost/privacy efficient way knowing the hard link between blockspace- parachain/parathread in the Kusama/Polkadot world ?
Cheers,