They can actually branch out blue mage to have physical and magical setups so it can actually fit in the recent party meta. Its better for them to try to make it to become a normal job and rebalance it instead of trying to make more blue mage contents only. Some adjustments are always required. Even the other jobs got balancing from time to time. So its possible if they really want to do it. They can add new battle systems to other classes in this expansion like white mage's lilies and other stuffs. So something unique for blue mage in entirely possible