I don't know how will companies pay to datum, it probably will be on fiat.
But datum will pay in dat to people who it buys their data from.
The companies will probably get a choice in what currency they will need to pay.
DAT tokens, BTC, ETH or FIAT would be my guess.
Is that somewhere described in the Whitepaper?
For an organizational matter it will be much more feasible to use the Dat Tokens for payment in these commercializations, but an integration with Btc and ETH will be very pleasant. The only certainty is that the application of the Datum concept will bring us better days