Can you outline, why 1. holds true?
I understand that it is a likely scenario, since delegators give commission to validators. However in a perfect market, where MR = MC (marginal cost equals marginal return), the commission would be just so high, that it covers the expense of running the validator. So in reality of course the return is slightly higher than the cost, but it might be that it takes some 100 years until this makes a noticable difference. But within such a timeframe there are heirs who don’t identify with cosmos and just sell their stake and buy lambos etc. So at some timeframe this will be mixed up anyway.
Furthermore there is another scenario, where big validators don’t charge any commission at all, because for them it is nice to have more voting power, since it turned out that many just delegate and don’t use their individual voting rights.
So I’d like to hear more why it necessarily must happen this way. For me it is possible that someone who wants to validate, because his/her own stake is big enough so that it makes sense, then well allowing delegation with a commission that matches the running cost of the validator nodes, means that the costs are paid by the delegators but there is no increase of stake in relation to other validators.
I totally agree to 4. It makes sense to think about this early, if it is a problem and there must be a solution that cuts off profits from someone, then it might cause a lot of trouble.
What are possible solutions?
a) force validators to sell atoms
b) force validators to donate atoms
c) slash validator atoms
d) lower the profits of the validators commission
So to me option b) makes the most sense, especially if the validator is allowed to decide what kind of donation can be done, for example fund some cosmos based startups. In that case the validator has an economic reason to do that, because he increases the value of the product he is highly invested in. c) and d) are mostly disincentivizing validators, a) can be sidestepped by new nodes as mentioned in your point 2. Of course the donation thing can also be sidestepped, but the question is if you want to do that, once there is a consensus for this solution to delegation centralization. You would lose trust of the community and that is very important to keep.