Add spaces: Ifastrology’speopledonotthemselveswanttobeinvolvedindevelopingwhatwemightcalltheastrologyofanewage,itwillbecomeextinctinafewgenerations,andwillonlybeusedasa"parlorgame".
If astrology’s people do not themselves want to be involved in developing what we might call the astrology of a new age, it will become extinct in a few generations, and will only be used as a "parlor game".