The New York Times just reported the first well-documented case of a trans woman who has been able to successfully provide an infant with full nutrition from her breast milk for several weeks. The breasts we grow on the feminizing hormones have the tissues to produce milk and route it to the nipples, all we need is an additional drug to trigger lactation.
I have talked to several young trans women who would very much like to become mothers. Not every transgender woman has such maternal desires. Neither does every cisgender woman. This is something every woman should be able to decide for herself. If I were much younger, this is something I would definitely consider!