For a Blockchain to remain decentralised, you have to limit the number of Utxos, because everything else can be compressed, but you need this full set to be able to produce new blocks, and for users to create transactions...
But that already sounds like Pools, and indeed, a trustless pool is a Blockchain (or call it a distributed event log if you want) with a hard limit on the size of UTXO set.
There can only be so many pools on Bitcoin, because Bitcoin too needs to limit its utxo set, but the limit is very large, and there is still shallow recursion (pools inside pools) if necessary.
Cross pools finality will always be slow though, but it will probably still be faster than banks finality (30 days).
