Is the Electoral College that is written into the US Constitution broken for modern times? One could say that it is not, but just needs to be more representative of the people.
National Popular vote, unfortunately you have by-passed the US Constitution and the reason for the Electoral Collage of giving small state and large states equal representation in the US Congress and voting for President. Under any national popular vote plan the candidates for President would just travel to the top ten most populated cities and the rest of the nation would be left out, making America more divided that it presently is, and giving more control to the two party system.
The solution is to use the Electoral College, and Congressional Districts be awarded electoral votes proportionally like in Maine and Nebraska. If the number is odd for the state then that single elector would be at large for the overall popular vote for the state. Electoral redistricting would be completed by a mixture of the state legislature to include representation from established third parties in the state to prevent gerrymandering. Washington DC will not receive three electoral votes but rather only the electoral votes based on population, since they are not a State, and do not have US Senators. Why does Washington DC have more power in their vote for President than States like Montana, Wyoming and North Dakota?
Finally all the US Territories will receive representation by population to include Puerto Rico, US Virgin Islands, Guam, Commonwealth of the Northern Marianas and American Samoa. Why can an American vote from any where on the planet, or even from the US Space Station but they can not vote for President from the US Territories? Territories are not a State so they will not get the two US Senate electors, but they would receive the US Representative electors based on the US Census, with not less than one elector per territory.
Veterans Party of America