Virginia almost never votes in a governor of the same party as the White House, 2013 is literally the only exception in modern history.
Trump is utterly hated in Virginia too, so the Republican's chances there look pretty darn small, no matter how good Gillespie supposedly is there. (Which I disagree with, Gillespie is a mediocre candidate)
Gillespie, like Cory Gardner, was a warm body at the right time - well, almost right time in Gillespie's case. Sadly for him (and good for the people of Virginia), I don't think magic is going to happen twice - now people are going to actually pay attention to how much of a partisan hack he is and also affiliate him with the President who Virginians (particularly in Northern Virginia) hate.