Bitcoin gold valuation has always been there on the futures market when it forked. It simply was on testnet and wasn't executed for the public (Nov 14th). Once the block explorer could identify the height, the number of blocks and exact number of coins can now be identified properly.
Market cap is the total supply x market price.
Market price has always existed since the Oct 25th fork. The total supply was unknown until Nov 14th. Coinmarketcap finally had it fixed.
It's not a threat. It's friendly competition.