Invention to solve traffic problem... perhaps some means of flying transport on individual basis.. like air balloons.. or flying scooters..
dust, dirt, chemical pollution is too much... Some invention is needed that is economical.
medicine to cure viral diseases.. cold, fever quickly.
cure for cancer.
some discovery / invention to make people move to rural areas and small towns, so that metropolitan cities do not become more crowded than they can serve.
an automatic cooking, cleaning assistant.
some way of seeing beyond an obstruction
very fast trains but cheap enough.
cheap bio fuel or green fuel..