I'll have to write up a full blown explanation of this but it's quite complicated.
The long and short of it, the GOP becomes competitive in the cities and the urban areas as a result of blowouts in the 2020s or 2030s by the Democrats, leading up to this Presidential election. The loss of Texas and the Sunbelt as well as California also force the GOP to become vastly more moderate and the Democrats rely on minority voters to power them.
The evangelical base is dead and the business wing of the GOP is more moderate, by far, allowing the GOP to compete in areas they wouldn't otherwise. The Great Immigration debate is done in favor of immigration reform and global warming is accepted by both parties as a serious concern, thus easing the GOP's path in many coastal states. Minorities, however, still vote heavily Democratic thus making Texas and California Democratic states.
