The idea of digital cash died the moment Satoshi decided on a hard cap. Hoarding and reluctance to spend is inevitable. That's what all humans do and no amount of cajoling will encourage them to give it up.
There might be some usage as currency if it ever becomes 'boring', but to get there it has to get through the speculative phase and become a store of value first. That implies a monstrous price.
Even then if you have USD to spend you're still going to prefer to get rid of that.
Satoshi's original vision may well be fulfilled by another coin, certainly not BCH, but that won't mean Bitcoin failed. It will have morphed into what its initial parameters dictated.
That’s a good point. Even if bitcoin implodes maybe it will lead to something that does fulfill his vision.
Governments usually appoint teams of scholars to control the overall economy of a country. These people have advanced degrees in business and economics from well respected universities and still get it wrong often. Without getting into the complexity of monetary policy, simply setting some automatic triggers won’t make a cryptocurrency exchange rate more stable.
You’re right, the coin you describe would probably have a more stable price, at least initially, but it would lose some of the advantages of bitcoin. Having a percentage based adjustable money supply would eventually lead to exponential inflation (the more coins you have the greater the number created by your fixed percentage). Prices rise when currency within a small economy is worth less than it was before. For a fixed amount, your coin would continuously buy fewer products than it could have before. When a currency is worth less, its exchange rate weakens when compared to other currencies. Exponential inflation would eventually make your coin worthless. I don’t believe there is an automatic mechanism that can be implemented in lines of code and left static for decades that can allow any cryptocurrency to be valuable when used as a true currency.