I actually think this should be taken seriously: The proof size for this “KZG verkle tree” construction is not sublinear, but still way smaller than for Merkle trees. All the KZG proofs can actually batched together into a single one; the only thing that needs to be transmitted is the intermediat KZG commitments that these need to be checked against. Proof size is therefore something like \log_k n - 1 group elements, where r is the verkle branching factor. In practice e.g. r=2^{16} and n=2^{30}, so we realistically only need one additional group element per proven position. That’s about 20x better than Merkle trees!
In terms of updating witnesses, an update does not touch all the commitments, so for each update only k \log_r n have to be updated. So using the KZG precomputation/updating techniques from this paper would allow efficient proofs and updates as per 5.(ii)
Even though they don’t fulfill all the criteria, I actually now feel that verkle trees are better than what we have considered so far. In addition, they provide another elegant construction for key-value stores in the form of “verkle tries”.
Thanks to @Pratyush for pointing out these properties on the twitter thread!
[Edit: I noticed I was using k to describe two different values. I now changed it so that k is the same as previously (number of reveals), and r is the verkle branching factor]