Interesting feedback. I think my mistake is that I predicted this to happen too soon. I think that what I predicted will happen eventually, but maybe a few more decades down the road.
Yes, the time span will be much longer.
For one thing that is an essential aspect that was overlooked and bridges the gap between "Evangelical strength in primaries" and the GOP becoming more secular.
Look for instance at Trump's strength among down market evangelicals. The key to this strategy is the gradual shift, and running candidates who can still get a slice of that vote, largely on economics but also promising judges and so forth. But the necessary slice decreases with each cycle.