This is yet another middle finger to the blue collar Whites who had traditionally been part of the Democrat umbrella. Remember how they pretty much admitted as much in that New York Times article a few months ago? They've clearly banked on a long term strategy that says "f**k white people". They've interpreted the demographic trends that whites are going to become less and less of the population, so just cut them loose now and build a coalition of brown. Whether that will work or not, I don't know. Until honkies learn to start thinking in ethnic terms, they're just going to continue getting pushed out of the picture, pushed out of the country their ancestors founded.
But politically, I am not sure what this accomplishes for him. The precious "Hispanic vote" is going to go largely Dem anyway. The only people likely to be affected by this announcement are those who will be convinced even more to vote against him.
As an aside, I would like to see someone with the financial means to do so simply start trolling all over Europe offering free transport to the USA. Just start dumping thousands of Europeans here, there may be a big demand to get out of there as their economy self destructs completely. I mean, if they're not going to be deported...