Republicans are perfectly capable of winning elections as long as their message resonates with people who work and pay taxes.
The more important trend we should be looking at here is urbanization, not demographics. People who live in cities are socialist by nature simply because their lives are built around having other people take care of 90% of their needs. That is what has been driving some of the most destructive policies we've seen in this country in recent decades -- including "free trade" and mass immigration. Basically, people who aren't allowed to own slaves will figure out other ways to get access to them.
You’re twisting yourself into pretzels to ignore the obvious. Urbanization is not the cause of this. Southern California was urbanized in the 1970s and 1980s, and it was a beautiful place to live in. Now it isn’t. Detroit used to be one of the richest cities per capita and now it’s in ruins. Even Minneapolis used to be nice, and now it has turned into little Mogadishu.
Immigration is the cause of all of this and we would have ZERO of these problems if these people weren’t even here in the first place. I seriously find it hard to believe you don’t already know this.