If Bitcoin hits 1,000,000$ mark, their market capitalization should be around 18,7 Trillions.
This is not doubling the market cap of Gold which is 11 Trillion.
I think this can happen sooner than later. We could get there if some money from institutions starts flowing to Bitcoin. Actually there are Trillions of dollars in state bonds that are yealding 0 or almost 0.
This can flow rapidly into Bitcoin, and at some point a part of that will come.
We just have to be patient!