Maryland enacted a law that would give its electoral votes to the winner of the national popular vote -- if enough other states do the same. So for the time being, Maryland is still in the Electoral College. Thing is, if enough states pass similar laws, such that 270 votes of the Electoral College would be subject to these laws, then the College would be stacked with votes for the popular winner -- even if the states sending those delegates to the College had voted for the other candidate.
I have grave doubts about the constitutionality of this law. It would have the effect of undercutting and rendering ineffective the Electoral College system described in the Constitution. So in effect, this would be Maryland and several of its sister states amending the Constitution of the United States.
Article V of the Constitution requires larger than absolute majorities, in several phases of the process of amendment (two-thirds vote in the House and two-thirds vote in the Senate, followed by ratification of three-quarters of the states). But if enough states were to adopt this proposal such that 270 electoral votes could be gained by it, in theory this would represent only a slim majority of the states and a slim majority of the population.
Whatever the merits of abolishing the Electoral College might be, this is not the way to go about it. If we need to amend the Constitution, then let us use the process already in place for doing so.