It doesn't seem like it will do anything in regards to the electoral college and Trump's presidency; the electoral votes that push Trump over the 270 needed come mostly from states without any real question as to how they swung.
However, there is a major impact in could have on the way politicians in the administration handle themselves, and in the way Democrats and more moderate Republicans act in Congress. It looks like she will have won the popular vote by considerably more than Gore did vs Bush; almost four times in fact. What this could mean is that Republicans thinking long term about their own careers, and Democrats looking for Hope in the future, know that Trump didn't quite get a mandate as President; if he fails in any manner, there's political will to be appealed to in attacking him.
It could mean that Trump is more likely to be impeached, since it heavily implies he's heading a bare majority coalition, and we know other Republicans wouldn't mind seeing him gone. If they think they can remain in power, or that the people who voted Trump will stick with Pence and their Congressional majorities if he's gone, then he may have a muzzle on him.
