Sam offers his suggestions for a way forward after Shelby County, in the New Republic.  The operative nub:

A new Elections Clause approach would forgo the attempt to freeze the status quo by forcing prior federal approval. Instead Congress could create a system of disclosure, as under the securities laws, making sure that all changes in voting practices for federal elections are recorded electronically with a suitable federal agency. States could implement the change after having some state official attest to why it was needed, and what would be its likely impact on voter registration, turnout, or ease of administration. This would force transparency and accountability on administrative conduct prompted by partisan or other malevolent objectives.

Far more (and eloquently expressed) here.