They did say "alternative classifications", and I'm getting the sense that this means it would be a medical diagnosis, rather than a psychological one. I think this makes a whole lot of sense.
My therapist never actually gave me a formal diagnosis of GID, but there are a lot of countries where you cannot get access to treatment without one. And down the road that diagnosis can cause problems - someone might be barred from entering certain occupations or kept from serving in the military or civil service, on the grounds that they have been diagnosed with a mental disorder. I'm not saying that changing the way it's diagnosed would remove all the stigma from being trans, but I think it'd go a long way in combating the myth that it's the result of mental illness.