It is not going to end well for the helpless innocent child. That is for damn sure.
The "mother" is likely using this child in order to be "trendy" in her social circles. She will casually mention "Oh, I have a transgender child..." in the same way others mention about their "tea cup" dogs or their de-clawed kittens.
Or she has some variation of munchausen-by-proxy syndrome.
Either way, this woman is sick, sick, sick.
I would posit that “mom” has been brainwashing the boy for some time now thereby robbing his innocence. Millstones come to mind and the Marianna Trench.
I can see this coming back to haunt a lot of parents as their rage filled children come looking for revenge.