I would imagine that the RC system will only make their surcharges for the Steem Blockchain higher. I’ve never used Blocktrades for delegating or to buy Steem with coins other than SBD, but if any outgoing service they provide now costs RCs, there will be competition to receive their services before their RCs run too low to guarantee the completion of their services, which I think would mean that they will need to charge higher fees to make sure that they can cover their RC costs.