And the exchange getting the bitcoin for free from the miners?I don't think so, but I believe if the exchanger is already having some funds at starting their exchange site and later we will get more amount if there are a developer is wanna for sign in their coin into the exchange site and they also get their bitcoin from giving a tax for their users.
Why should miners give free bitcoins to exchange. Everybody is doing their business then how come a freebie will come to play here. Miners will need to sell some of their block rewards time to time for managing their mining activities. Then obviously they will hit exchange for the need of running costs for the mining farm.