Simplified Active Validator Cap and Rotation Proposal

[aelowsson]

@jgm

A system that leaves validators in the activation queue until there is room for them due to others exiting seems to provide superior results for all three key properties listed at the beginning of the proposal

I think a queue could lead to various security issues, since such a quasi-permissioned system will enable stakers “on the inside” to exercise undue control over the chain. It can also lead to rent-seeking behavior.