Mostly Agree
However, a combination of terraforming and genetic engineering could be possible. For example humans engineered to tolerate high levels of CO2 and other greenhouse gases needed to keep Mars warm after a large portio of CO2 is converted to O2. Increased tolerance for radiation and the impacts of low g are other possibilities of more immediate use. I agree completely that humans will never be able to survive on other worlds in our solar system based on biological adaption alone.
Regards,
Mark