Your last two paragraphs seem illogical. You say that as the Democrats aid lower classes and immigrants the result is that they become Republicans as they seek more uplifting ideas. Then you draw the strange conclusion that they are bombarding us with HIGH quality new immigrants and their purpose is to have them as future Democrat voters, and that without them the D party would fade away.
Sorry for any confusion, I'll confess that sentence is less readable than it should be.
But if you look again, you'll see that I intended: "not just high quality new immigrants, but [also, and] more to Democrat purposes: the worst of the worst, [to be] future Democrat voters."
Is that better?
Here's my point: records show that since IQ'S were first tested (Stanford-Binet, 1916) average scores have slowly increased amongst all groups.
It's called the "Flynn effect" and is especially pronounced among new immigrant groups, second & third generations, etc.
So I merely observed (only half facetiously) that as their IQs increase, people figure out that Democrat Big Government nostrums are really intended to benefit only Big Government, and to keep everyone else in a state of dependence.
Such people begin looking for political solutions which do not require ever more taxes, regulations & control, etc. and thus can finally become persuadable to more conservative ideas.
So, as the second, third & fourth generations of immigrants begin to move up, and become more conservative, Democrats have to fill in their ranks with ever more new immigrants, and the less likely those immigrants are to move up, the better for Dems.
Does that seem logical to you now?