Step 1:To challenge to gold in 20 years.Step 2:To challenge the world's No. 1 currency within 50 years.
I can't read this line on any of the pages of the Bitcoin white paper. I wonder where you get this assumption @OP?
Anyway, as far as I remember, the Bitcoin whitepaper[1] describes the vision of Bitcoin being a peer to peer electronic cash transfer without relying or trusting any financial institution. So I guess the long term goal of Bitcoin is to enable individuals not to trust the financial system when they are executing electronic transactions. It isn't to challenge gold or currency but
the current financial system.
[1]
https://bitcoin.org/en/bitcoin-paper