Sorry, you are mixing and matching concepts from reading too many articles on HFT.
> the dark pool operators make money from the HFT's not in terms of the commission, but in terms of collocating fees,
No. Dark pool don't really charge collocation fees. Barclays LX didn't. Most dark pools are in Weehawken and it's just a simple $500 cross-connect from your existing trading system.
> market data fees
It's a dark pool. There is no market data to charge a fee from.
> , and the right to be one of only a few HFTs allowed in the dark pool via collocating, ie exclusivity.
Not in the case of Barclays LX. They let every HFT in at very low rates which is the entire point of the article.