I think the VRA is still relevant when protecting Hispanic voters; I mean, without VRA protection, the Hispanic districts would be at the mercy of Republicans who are all too eager to create pseudo-Hispanic districts that elect white Republicans.
For black voters? Not really relevant, since Republicans are eager to pack them into as few districts as possible. I can't really think of a single state where they'd try to crack black voters. And Democrats would love to be able to drop VRA district percentages below 50% (certainly in most areas a black VAP of about 40% would be more than sufficient to elect a black candidate) and share the wealth in other districts.
The problem with using the VRA to "protect" Hispanic voters is that Hispanic voters aren't as monolithic as African-Americans. A good percentage of Hispanics vote Republican - much more than the 10% or so of African-Americans do. "Protecting" Hispanic voters by making sure Hispanic districts elect Democrats effectively disenfranchises Republican-voting Hispanics (and, since race is all that matters under the VRA, whatever other Republicans of whatever other race are put in that district to make sure the "correct" percentage of the "special" minority are put in that district, but not more).
The VRA is an anachronistic law whose time has long past. If anything, it ensures greater political division among races instead of integration. There's no sense being a black Republican in a VRA district, since no Republican could possibly win. If the VRA didn't exist and geography and compactness were to trump all instead of race, there would be more competitive districts and courting African-American votes would matter more to Republican Congressional and local candidates.
