The SIMD-0228 precedent
That 66% bar is where the last major inflation fight fell short: Multicoin Capital's Tushar Jain and Vishal Kankani authored SIMD-0228, proposing to tie SOL issuance to staking participation and to cut emissions once the network reached a well-secured level.
It drew 61.39% approval against a 66.67% requirement, even as roughly 74% of staked SOL weighed in, a turnout that ruled out any low-stakes formality.
Validators staking 500,000 SOL or less voted against SIMD-0228 over 60% of the time, while larger operators leaned the other way.
Treating the SIMD-0228 result as 100 units of decisive stake, split 61.39 For to 38.61 Against: flipping just 5.28 of those points from Against to For clears 66%. Reclassifying 7.92 points as abstain does the same job, since abstentions drop out of the denominator entirely.
Bringing in fresh stake that never voted at all takes more, about 15.84 new For units for every 100 old ones.