That's exactly the point of the Compact. It does not get rid of the EC. It requires the members of the compact to direct their EC votes to the winner of the popular vote.

As we have seen with so-called “faithless electors” (people who vote at the electoral college but not for the winner of their particular state - which has happened many times), there is nothing legally to prevent a state from directing their electors to vote in whatever way they are directed by the state law. If it has not been “unconstitutional” to do so for 250 years, surely there wouldn’t be a new “originalist” ruling that changes that, would there? (I make a joke.)

But I agree here, it should be done with a Constitutional Amendment. Suppose, for a moment, the Compact gets enough traction to cross the finish line and it becomes effective. Then a state, for whatever reason changes its mind (note the Blue Tsunami of two days ago, or the Red wave in 2012) and pull out. Suddenly there are not enough states in the Compact to hold it together, and we’re back to the Electoral College nonsense.

The only real way to end this misrepresentation flaw is by Constitutional Amendment. It’s hard, but it’s even done almost 30 times, so it’s not impossible. Time to get going.