I was not aware of this. You really want to kill small pools don’t you? 
(Just joking here).
You may not like that but even if that’s not the most urgent and important, and that’s another debate, but I would instead advocate for:
- Imposing 0 fixed fees for all pools
- Having the same variable fee for every pool voted/chosen in some way, in a regular basis.
This would set sane basis for a real “representative democracy”, that you wanted to implement in the first place, as all pools would have the exact same RoS and then, the only basis of choice for a pool for users, would be “who do I trust more?”.
By the way you did not answer to that, (don’t you think it’s a problem?):
c-At the same time Introduction of a0 and variable RoS also impact negatively Sybill-resilience on an other side, because it incentize users to delegate according to RoS, so it discourages the natural tendency of users to delegate to someone or some organization they know directly and trust. This latter behavior is a very powerfull brakes on Sybill attacks.
Then large pools would be very profitable and some smaller could be still be profitable but less, for the pool owners, but it would be the same RoS for delagtes. Let’s take your example again a huge has 30$ costs and gets $5000, it’s highly profitable for the owner. On the other side a small pool as 30$ costs and gets 50$ it’s a much less profitable for the owner but it still is, so it is still viable. But you can delegate to both without any change in RoS. So it would preferably lead to only k pool (the Nash equilibrium), but maybe more if people distrust one another too much and want to create separate pools despite financial incentives.
That will be all for me, for today, I will answer your other message tomorrow!
Cheers, and thank’s for this very interesting discussion.