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To reiterate, Republicans depend on winning the white vote by inflated margins to offset the minority vote in Texas, Georgia etc. Republican's margin with white voters come from silents and baby boomers. As they die off and as millennial whites age into peak voting years, the GOP margins with white voters will recess towards the national average and that is not enough to sustain GOP majorities or even pluralities in TX and GA.
This assumes that virtually no Gen X-ers or Gen Y-ers will be getting any more conservative as they age. In other words, for most people, once you choose and ideology and a party affiliation, they never change. Not a good assumption to make.
While turnout varies, individuals rarely switch parties.
