Standardized tests are not going away. Selective “test optional” schools offer this option because they don’t have to include unsubmitted scores in their published averages. This policy keeps the schools looking competitive on paper while allowing them some flexibility in admissions. It’s not done to benefit the bright, hardworking kid who just doesn’t test well. Kids who don’t submit scores must have other things going for them, such as a very rigorous HS curriculum and good grades, interesting ECs, etc. And @ucbalumnus is right. Colleges can make a good guess about your likely SAT score range by looking at your zipcode.
The SAT came into being as a way for smart kids from the sticks who didn’t go to prep school to prove they were college-ready. Some schools are not rigorous, and there is such rampant grade inflation in many that a good GPA means nothing without some other context provided by standardized testing.