Incoming essay from Virginia!I posted something to this effect, in terms of electoral success, in another thread:
https://uselectionatlas.org/FORUM/index.php?topic=231970.msg4968986#msg4968986However, there are more issues at play here:
1. He's going to cost them voters. I really don't care what Trumpistas say about this, because they are probably blinded by their lust for Trump, but there are no massive registration surges for Republicans going on. He's simply inspiring existing Republicans at the expense of moderate Republicans who probably think their party has finally gone off the deep end. Simply put, if he was actually inspiring many new voters to join the GOP's ranks, it would be reflected by changes in voter registrations. So far, it is not - And it's not like Trump is investing money in registering new people, either. He's being cheap as hell and that will also cost him in the GE.
2. A positive change - Trump has effectively changed the party agenda unilaterally to reflect what a large part of their voters (working class whites) want, but have been denied for so long. They don't want destructive free trade agreements, they want to raise taxes on some rich people, they don't want immigration reform, etc.
He's finally put an end to the establishment ignoring huge amounts of their voters in favor of GOP donors. Whether or not you agree with these new policies, they better reflect what their voters want and not sh**tty donors/politicians want. Once Trump is gone, establishment Republicans will not be able to easily return to the previous agenda. The voters won't have it.
3. In addition to the probable loss of some moderate Republicans, Trump has effectively stained the GOP in the eyes of non-white voters even further. I wouldn't be surprised if the GOP barely brings in 10% of non-white voters, down from Romney's 17%-18% in 2012. Not only that, but he helping to make Hispanics a monolithic Democratic voting bloc and it will take Republicans many years to even begin to win back some non-white voters.
This is
extremely bad news for them given how fast the non-white electorate is growing. Every 4 years it takes over about 2% more of the electorate. Right now it's at about 30% for 2016, and in 2020, it will be 32% - 33%, 2024 - 34% - 35%, and so on. If they don't figure out how to win them back soon, they will not be able to win the White House for many years.
Those are the most obvious and most significant effects, in my opinion.