Is it likely that in the near future transgender people will be able to transition via pure genetic therapy rather than surgical and hormonal replacement methods?

Anything is possible, but the science of this is in its infancy. I would guess genetic transformation would be at least a decade away if not considerably more.

I would think - although David would know better - that some aspects of sex reassignment surgery would remain in any event. Genetic therapy after development of   is unlikely to result in a complete transition of morphology for structures set early in ontogeny, e.g. external genitalia.