Actually, rather than ask Jim Horn what happened to the Lost Colonists of Roanoke, we should ask Neil Gaiman. In Marvel 1602, his series published in 2003–2004, he posits that Virginia Dare made it back to England:
Meanwhile, the ship Virginia Maid arrives in England from the New World, carrying the young Virginia Dare, the first child born in Roanoke colony, as well as her hulking Native American bodyguard Rojhaz. They are taken to meet the Queen only for a flying assassin to snatch Virginia. Rojhaz quickly disables the attacker, but Virginia has transformed into a white gryphon. Rojhaz subdues Virginia, and Strange bespells her to human form before Fury sees her transformed. She has strange shapeshifting powers, and Strange suspects she is the cause of the disastrous weather. Fury interrogates one of the assassins to learn who sent him. He is told that it is Otto von Doom, ruler of Latveria, but Fury is too late to stop one of Doom’s machines from killing Elizabeth with a poison gas released by dropping a pill into aqua regia.