Your point about owning only a promise on a promise stayed with me, because most investors never check the chain behind a brokerage account. Do you think tokenized stocks would fix that, or would the same custodians simply control the new records too? For a small saver, the difference between holding an asset and holding a claim on it feels worth understanding first.
Tokenization WILL fix the double spend problem and get rid of the ghost shares. That is the easy part.
But, now, how to buy shares? Can you just go to the block chain? Or do you have to go through an exchange? This will be a HUGE battle. And there is a lot of money involved in moving the market.
However, in the end, the stock market will go away. Stocks will go away. Corporations will go away.
In 50 years, there will be no corporations, and the businesses that are left WILL BE! non-polluting and socially conscious. (or they won't exist)