Nearly every young player who does well ends up getting compared to Tiger. I remember when Spieth, Rory, Jason Day and others were the next Tiger. I don't think there is a next Tiger. There is a big difference between having a really really good run and having transcendent talent. Morikawa is a Cal Bear so I hope I'm wrong, but I think he is in the former category and not the latter. I think its pretty likely the answer is something between 0-2 additional majors, probably more toward the 0 end of the spectrum.