Asians and hispanics married with whites at roughy the same rate, if I recall, around 20 percent for each ethnic group. However, blacks very rarely rarely marry whites, or ony other group, except blacks. The article was bemoaning the fact that although the US would become a more homogenous "tan" country (as opposed to a "white" country) blacks would still be on the outside.
As for Asian inter-racial marriages of Asians with whites, this is highly variable depending on the size of the Asian community. In L.A., where the Asian community is huge, there is relatively little Asian inter-racial marriage because the community is huge. Other places where the community is smaller, hence slimmer pickings, they are more likely to marry outside their race.
So NP-INCOMPLETE, you can relax because there will still be a pure Asian ethnic group. Unfortunately, you will have to live in L.A. to find it.