You could design a system (website?) where people can vote with signed messages. The signatures and balances could easily be verified.
A web site would be too centralized and unsecure to record a vote for an important development update.
What would be maybe possible is a
sidechain that records only PoS votes. It could be merged mined with the Bitcoin blockchain and only "live" as long as the vote lasts.
A challenge is to ensure the miners secure the sidechain, to prevent manipulation by "double-spent votes". So an agreement must be reached with them or an incentive system established. But I think security requirement for this sidechain should also not be too high, as manipulation can be easily detected afterwards, and then the vote could be repeated or the double-spent votes would have to be deleted.
Another challenge is to find a time interval for the balances being "recorded". One could solve it determining a fix block for this, and everyone wanting to vote must prove that he owned the UTXOs at that point of time.
The biggest problem I have with something like this is that it gives exchanges (or centralized wallet services, do any still exist?) an extremely heavy vote, while users with deposits at such places get no vote.
That's also a problem, that's why I think PoS should never be the only form to vote. In the case of soft forks, I would split it 50% PoS and 50% miner agreement (both over 75%, better over 90%).
I think there was something like this at one point. Perhaps it still exists?
Don't remember. Anyone knows?
(Perhaps the "withdrawal" of the proposal was premature. The sidechain idea is intriguing me, would love more input to it.)
