S3, Rank Reset

Hi everyone,
Does anyone know exactly what end of season, rank reset does?
I can read you keep your final rank and it will carry over. E.g. I finish Diamond 1, so I will start S4 as Diamond 1. But will the points carry over or do you start from 0? If all the points carry over also, then I can continue to grind for Master 5. Those already Master 5, what's the incentive to continue playing ranked? (beside it's fun) If you only just recently hit Master 5, the chance of hitting Top250 will most likely never happen and the race is lost, the point gab is just too big