The electorate changes, its demographics change, people need to adjust.

Hispanics are more naturally conservative and mostly align with Dems at the moment because of immigration policies and social issues. But as they Americanize, LatAms, at least so far, tend to not care about immigration issues as much and tend toward the view of a fair visa system and rely less on state services, as they integrate. As this happens, Hispanics eventually are likely to break even just like the rest of the population. Then people on one side or the other will prefer electoral votes over pop votes again.

So, you see, a gen or so, we're likely to see Hispanics move to the right, and then the Dems will find a reason to antagonize their new views (like they now antagonize their previous pet group, the working class union workers who abandoned them).