The Texas Failure
In many ways, it's possible to see the Texas decision as the end-point to a process begun by two key Warren Court decisions, Baker and Wesberry, which deemed it proper for the Court to intervene in the redistricting process to ensure fair representation. That said, some of the blame for the setback should fall on the plaintiffs--who gave Anthony Kennedy, the key vote in this case, a way out by simultaneously making a Voting Rights Act claim on two specific districts; and then weakened their case with a transparently absurd claim that mid-decade redistrictings should be held unconstitutional.
Whether or not the Court had a legal rationale for overturning the Texas map, the practical result is a real setback for anyone who hopes for competitive elections.