in theory, we could have 10 witnesses only. If the chain is super easy to copy and past ( i mean really super easy), it would always be a fork if they go crazy.
There must only be enough to not heist the chain.
But that lead to the problem of security will never be enough in term of looting pools.
IMo the theory would be: Biggest stakeholder x10 ( or more) of potential loot. If lower is not worth the risk. Special if Witnesses are the largest
20 is IMO a really good number. Maybe at some point, the rotation can become bigger to top 40 ( if enough witnesses are here to spread higher earnings to more).
Would it be needed? Maybe. But I think to have more witnesses would never hurt and DPOS is pretty solid. Special with a working token distribution.
it's about the rotation and distribution, not to let them act like the 20 elected.
If there would be an attack, in theory, the next replacement candidates need to have a reason to be up to date.
That works with money and rotates from the top to 33% more to top 40 would bring more security.
And yes it would be a tradeoff between efficiency and security. On a larger scale, security matters more than efficiency ( even 40 are pretty efficient, but the risk of 8 doesn't work is also high to loss consensus).
But as far i remember there is some solution from it if witnesses would loss connection to each other from blocktrades.
An example was the US losing its connection to EU.
In that example, it would work.
whatever. looks like you are an idiot