ll Knowledge" system would be more suitable for public blockchain verification, there is no sense in wrapping stuff in ZK for the hell of it.
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These things are not going to be any better than SPV at network security, might they offer a trusted solution that is scalable? Hopefully. But other than that no one will replace a full node with zero knowledge unless they dont care about what code they are running and in that case why even run a node?
I'm not ZeroSync evangelist nor I have any interest with them.
That said, I think you are thinking to zkSNARKs, but SNARKs can be also non-ZK. Their use is justified by being "Succinct", short proof (and quickly verifiable). Also ZK-Rollups, despite the name, are not zero knowledge, they use SNARKs because of succinctness.
So, I don't know if ZeroSync idea is good for blockchain size reduction (because any serious evaluation of schemes of that complexity should require a careful study of the proposed solution) , or if it will be accepted (I don't think so to be honest), but the usage of SNARKs to have succinct and fast checkable proof is brand new but well established.. confusing it with ZK flavours is not a good service to be OP imho