If you're going to remove the non-membership of mining and require certified (and ... presumably licensed by states, since the process will make it easy to pin them down) you might as well eliminate the mining, use signatures, and call it SWIFT.

There are perfectly legitimate uses for signature based systems— they have useful security/performance tradeoffs— but they're very much at odds with Bitcoin's security model. In Bitcoin mining is anonymous (in the sense that it has no membership) as part of the process of making it decenteralized and somewhat censorship resistant.

Anything that lets you tell if blocks are from the "same dude" creates hooks to force miners to only mine particular transactions.

(WRT "protocol changes", the coins produced by the coinbase transaction cannot be spent for 100 blocks)