The most likely advances within the next 20 years revolve around stem cells and cloning. Already extensive work is being done and cloned ears, skin, and other body parts are being used medically today. From the ears grown using a patient's own tissue and stem cells (DOD funded this for veterans who lost ears in wars) they are now advancing into researching growing genitalia for soldiers whose genitals were blown up from land mines. There is also initial work being done on growing artificial hearts from a patient's own tissue so no rejection drugs are needed. And finally, there is already research into growing ovaries and the uterus from tissue and stem cells for women who lack them.
What does this have to do with MtF transsexuals? Consider that we already know how to remove and/or replace chromosomes in a cell. So imagine taking stem cells, removing the Y chromosome and replacing it with a second X (your own X or the other X from your mother or father if available). Now you have an XX stem cell that won't be rejected by the body. Use these stem cells to grow ovaries. Transplant the ovaries and you no longer need to take estrogen. Your body produces it.
The next step would be to grow and transplant the entire reproductive structure, ovaries, fallopian tubes, uterus, cervix, etc., and attach to the neo-vagina. The neo-vagina and the male hips would preclude natural delivery of a baby (male hips are fused, female are not) but a TG woman who did this could conceive, carry, and give birth via C-section.
None of what I wrote above is "science fiction". It's not here yet but as I noted some of the precursor tech is here today, like growing ears and regrowing genitalia.
P.S. FtMs will likely be interested in the progress of the genitalia reconstruction efforts as the technology developed there could be used for them too. In short, within 10-20 years, I would not be surprised to see a TG MtF make the news that she had undergone such transplants, conceived, and given birth. This would not surprise me in the least. I'll be far too old for that by then but some young TG woman will be able to fulfill her dreams of being a woman and a mother someday. And while I'll be too old to benefit from that, I'd love to live to see it.