Regarding permissionless network. Delegated currencies, like DPoS steemit or DPoW bitcoin, has a potential problem with possible transaction moderation. Pools or witnesses can censor transactions from known annoying persons, and people can vote for these pools or witnesses with their stake or hashrate to exclude annoying person from the network, put assets on hold or even rewrite transactions like it was with ETH. I think good enough solution we can come with is delegated block signing by master nodes and voting for trusted block signers run by an algorithm. Master nodes can form consensus to exclude slow and messy peers from signing, master nodes don't need any approval from stakeholders, with big enough deposit required for master node setup there will be no room for Sybil attack. Optionally, there can be even some penalty to deposit for unhonest signers. It's still delegated PoS without randomness and network reorganisations, so block time can be very short and block size can be huge. Block chain can have 200tb of data and run fine since master nodes rewarded for their service and can afford high speed connection and huge storage. Instead of spending millions to securing network with hashrate there can be an incentive to build decentralized infrastructure for block chain storage, so it can be a network of millions of master nodes with current price people pay to miners.
Since too moral or annoyed master nodes get kicked out by an algorithm for messing with transactions network become provable permissionless. Or network can just kick out voted witnesses until reelection like it's already done in DPoS for network delay, but for transactions delay too.