Even if it was applied retrospectively, Trump's children would be US citizens by dint of him being a citizen (if his mother was a citizen at the time of his birth, his paternal grandfather's immigration status would be irrelevant).Trump's plan to end birthright citizenship guaranteed by the 14th Amendment means only one of his children, Tiffany, would be a citizen. Don Jr., Ivanka and Eric were all born before Ivana became a citizen and Barron was born before Melania became a citizen.
In any case as Darat clearly implied, the duskier the hue, the bigger the problem.
If his mother was a US citizen he'd be fine.LOL.
But my question is to Trump in particular. His grandfather was an illegal German immigrant to the USA. So if the Trump Deportation rule is applied retrospectively, Trump is not a "natural born US citizen" and is therefore unqualified to hold the position of President.