Liberal YouTubers

It wasn't that you couldn't vote unless your grandfather could. That would be a permanent ban on voting for successive generations as well.

It was that states implemented literacy requirements for ballot access... only to find that there were plenty of illiterate white people too. So they said that you could ignore the literacy requirement if your grandfather had been able to vote.

As for the question in the OP... they've already killed major portions of VRA. It won't be a surprise if they decide that it can't be used to require adding majority-minority districts when redistricting. That could make for some very interesting debates within the party in blue states after the 2030 census (particularly in states that are losing seats like NY and CA)