Nice chart amincd. Good observations all round.
Thank you for the compliment.
The reason behind the Au/Ag idea was that because bitcoin is so good in these categories, demand to hold it as money is extremely high.
I don't believe it will be any where near as attractive to hold on to it in the future as it is now. Right now it is going through a rapid growth phase, which has a natural limit due to the finiteness of the global economy. Whether that limit is 100%, 50% or 1% of the global economy, it will inevitably reach it one day, and when it does, the rate of value increase will slow to the rate of growth of the global economy.
Even now, with value growth of 100% a month, it is still being sold and traded in the tens of thousands of BTCs a day.
Bimetallic currencies were used extensively over the ages, it is easy to read up on how they worked. I do not know why people started using Ag in history since in theory the Au price can go as high and you can just divide it down. Maybe it was simply a physical issue, Au coins became too small or you had to mix them with too many other metals and they became difficult to validate the gold content easily. If the only reason was divisibility, then in theory if someone starts a 210M cap chain with a 500 BTC block nobody is going to be interested in it, they'll want only the scarcest stuff. If it is a more fundamental issue of demand for more stable pricing, then Ag will flourish. However, it will not make the AuBTC go away - of that I have confidence.
Yes that is the reason. Gold and silver have different properties that give them distinct advantages. Gold is difficult to make small value purchases with, because the mass that's needed to transfer is small and easily lost. Silver is more difficult to make large value purchases with, because it becomes heavy and costly to transfer large value in silver form.
A gold bitcoin will have no such differences in its quality as a currency from a silver or copper bitcoin, because any amount is easily transferred (e.g. 0.1 gold bitcoins versus 1,000,000 copper bitcoins is equally easy to transfer).
Right now, the biggest short-coming of bitcoin is that it's not widely adopted and thus a coincidence of wants involving bitcoins is rare. Promoting one type of bitcoin is better at over-coming this than different variations which will fork efforts and make each less effective.