Extensive use of Roundup Ready crops leads to evolution of weeds that are resistant to glyphosate. How do you prepare fields for cropping if all the weeds are

Extensive use of Roundup Ready crops leads to evolution of weeds that are resistant to glyphosate. How do you prepare fields for cropping if all the weeds are resistant to herbicides? Use stronger herbicides? How is this not an environmental disaster? What happens when altering the gene of a wheat plant to make it resistant to rust ends up adding a cumulative poison (e.g. a protein or prion associated with the rust resistance) causing the body to leech calcium from bones? Over 30 years we figure the gene was safe, then comes a 100 year long epidemic of brittle bones due to the rust gene being forgotten and no un modified wheat being available to breed clean strains from. Or leaving the food chain entirely: what about living in a world where you are not allowed to grow food plants in your own backyard and collect the seeds yourself to provide for next year's crop? Why do we have to increase the food supply to feed an ever-expanding population?