But there are other incentives to owning accounts, and specifically to centralize mining. A power vacuum will always be filled.
What kind of incentives are you talking about?
In my unpublished whitepaper, I have cited the research which has explained that economic control over fungible resources invariably become power-law or exponentially distributed. Try to find an exception in nature.
I don't contest that tendency for fungible resources.
Of course for non-fungible resources, such economic control over female vaginas is not centralized. (But to the extent control over humans is fungible, e.g. via debt and mass media, then control is centralized)
Sex industry demonstrates that humans are also fungible (for the most part).
Impossible to prevent selling accounts.
It's impossible to prevent that completely but you can make it very risky for the buyer. In my model, an account must possess a certain minimum account balance for minting (the value must be chosen with care). As a result, the buyer of an existing account must fill it with some money to be entitled for building blocks, while the former owner will still know the private key (which is unchangeable) and could steal the coins back at will. Considering that the most probable reason why someone would purchase existing accounts is to attack the coin, the sellers of old accounts would have an additional (altruisitic) incentive to grab the coins since they could say they did it for the public good.
It certainly is possible to create an asset that no one wants to buy and thus there is not point in discussing a design that will have 0 investment and security.
The main idea of my concept is to create an asset (minting account) that people only buy for one specific reason, namely to get interest on their stakes in the underlying currency. In contrast, purchase for resale is disincentivized.
Sorry you can't defeat thermodynamics. You need top understand why some things remain decentralized and others don't. The key word is obviously fungibility.
Obviously, my design leverages the concept of fungibility to maximize decentralization (via interests for every minting account owner and the minimum account balance required for minting) and security (via the extensive time needed to buy the majority of accounts whose creation rate is limited).