While change has been slow, at least there has been some momentum. In the years since 2000, there are at least some actors of Asian descent in lead roles on American TV, even if you can count them with your fingers. And that may even be more about the sheer volume of TV, rather than replacing caucasian actors.
There’s Lucy Liu on Elementary, there was Daniel Dae Kim on Hawaii Five-O, who quit after producers refused to pay him the same as his white co-star, Priyanka Chopra on the cancelled Quantico, Maggie Q on the cancelled Designated Survivor, Ken Jeong on the cancelled Dr Ken, Mindy Kaling on now-ended The Mindy Project, Darren Criss (whose mother is Filipino) on Assassination Of Gianni Versace and there is the cast of Fresh Off The Boat, led by the phenomenally funny Constance Wu and Randall Park.