BioWare has long-term plans for “Dragon Age”. There are even ideas for a theoretical “Dragon Age 5”, if it should come before part 4.
According to Mike Laidlaw, there is no planned end for the “Dragon Age” series. There is a long-term plan that looks ahead to two more games. In this case they would be part 4 and 5, but so far no project has been announced yet. The statements of Mike Laidlaw are, as I said, purely theoretical.