Granted but Donald Trump becomes Supreme Overlord of the Texan Nation and building the Great Wall of Texas to block not only Mexico but the US breaks the economy utterly due to resources for building and upkeep. Then, the wall's construction also offends others diplomatically and they unleash trade sanctions upon you. With a large population, limited arable land, a broken economy and no trade, the land soon descends into anarchy and savagery. Horrified, Mexico proceeds to colonize Texas. The End.
I wish for immortality and eternal youth.