"Decentralization" isn't the end-goal so measuring it here isn't all that meaningful. Personally, I care about: 1. How hard is it to censor the network. 2. How hard would it be for some major player to enshittify the network. Furthermore, while the fediverse has a single axis for decentralization, BlueSky has 3: number of "big index servers", number of PDSs, number of domain names (how many people own their handle):…
BlueSky's primary defense against enshittification is user account portability. I wonder if people would actually migrate or if they'd just get boiled.
Bluesky isn't decentralized, anyway, because of the PLC directory.