I appreciate the points that you raised but I do think you have overlooked the power of the purse. Yes there are rich democrats but there may be very limited poor republicans. Tax cuts don’t have wide appeal. The Reagan Democrats voted for Reagan and the Bush duo. I am pretty sure this included a lot with immigrant backgrounds. So it is possible. However if their jobs are exported they quickly turn to Democrats. If that is their foreseeable future then they will be forever democrats.
For an illustration of my point, you might look at the great difference in voting patterns between two subsets of the German Immigrants, who came to America in the 19th Century. Milwaukee drew predominantly from the Left side of German social identification; Cincinnati from the Right. The descendants still reflect, to a considerable degree similar attitudes. (Even Cincinnati Democrats tend to be less "kookie" than the thugs trying to intimidate others in Wisconsin, after the Tea Party triumph, Statewide, in 2010.)
Another contrast would be between those who settled in enclaves in ports of entry, with their countrymen who went into the hinterlands. Not only are certain national origins more apt to vote Left than others, generally, but there is considerable variation, in inclinations, reflected from arrival on. (See, for example, the discussion of the Goldwater defeat in An American Immigration Policy.)
We need to stop pretending that people are interchangeable. That, as previously stated, is an insult to all.
The point is that we should treat all with respect; but citizenship should be reserved to those who share the values--including the cultural values--of rooted Americans. That means those who honor the purpose stated in the Preamble to the Constitution.
William Flax