I have a few thoughts about this.
Firstly, yes, being a living organ donor is a huge thing. But despite the risks there is an established practice of this in cases where it is possible for the donor to survive without the donated organ. People donate one of their kidneys or part of their liver to help people with kidney or liver failure. It is most common for these to be directed donations because a lot more people will be willing to go through something so extreme to help someone they love than for a stranger. I don't really see that this is all that different. OK they're not doing it to save their loved one's life, but at the same time, donating your uterus when you no longer need it is less risky than donating one of your kidneys and relying on your remaining kidney to keep functioning. I don't have a sister, and I doubt anyone would want my uterus, which has been through five miscarriages and a C-section. But if someone close to me did want it, I'd probably rather donate that than a kidney, to be honest, because I no longer have any need for it.
There is little to no risk of this creating an organ trafficking problem, because the number of women who are in the market to receive a donated uterus is so small. This is because the overwhelming majority of women already have a uterus. We know there is a market for women who cannot conceive using their own eggs to receive donor eggs. And we know there is a market for women who either have complete uterine infertility or for whatever reason do not wish to go through pregnancy and childbirth themselves to use surrogates. But most women who use surrogates fall into the latter category, and are not doing it because they do not have a uterus. Whilst there are ethical issues with both egg donation and surrogacy, these are well developed medical procedures which are barely more complicated than a woman doing IVF using her own eggs. A uterus transplant, by contrast, is an incredibly complex, risky surgery with a high failure rate. It will be significantly more expensive than using a surrogate, with more potential complications and much lower chances of a live birth at the end of the process. If you were in the business of exploiting women for their reproductive organs, you'd continue to focus on egg donation and surrogacy, because that is where there is money to be made. The number of women without a uterus who have the money to pay for this surgery (even if you can find a poor woman willing to part with her uterus, who is a good match for the recipient) is so vanishingly small that it's just not an interesting market for exploitation. And I suspect that as with all transplant surgeries, it's quite difficult to match a donor and recipient, which is another reason why directed donations from close family members are preferred.
If anything, what this does is slightly reduce the demand for surrogacy, because it gives women with complete uterine infertility the chance of carrying their own babies, rather than having someone else do it. It's debatable whether the physical risks of donating your uterus or going through a full term IVF pregnancy and childbirth are greater for the donor (at the end of the day the donor is just having a hysterectomy, which is major surgery but not particularly high risk) but at least from the baby's point of view, there is no issue of being separated from their birth mother at birth.
As for the potential for trans women to have uterus transplants, it's just not going to happen. Ever. Anyone who thinks it will simply doesn't understand how the female body works. It's incredibly difficult to transplant a uterus from a female body to another female body even if you find a donor who is compatible with the recipient. A uterus from a female donor is never going to be compatible with a male recipient, because, well, he's male. He doesn't have space for a uterus in his abdomen, he doesn't have the hormonal processes to support it, he has a Y chromosome in every cell of his DNA. Even if it could be plumbed in at all, which it probably can't, his body would reject it immediately and he could potentially die. It's just a complete non starter and anyone who believes otherwise is a fantasist.