Replicating what I had already suggested on twitter: https://twitter.com/wmitsuda/status/1582624228213657601
Keep deprecating and bootstraping new goerli and sepolia in alternate years to educate people that testnets can be discarded and testnet eth is valueless, give initial allocation to known set of reputable community members, faucet admins, etc, for redistribution
That would “only” require new chainspec deployment/removal from clients every X months, no custom testnet protocol development effort. Infra providers possibly happy because testnet chains will be always small and eventually thrown away after some period of time.