I don't think so? As far as I'm aware, Gamebryo was just the renderer part anyway and it was already heavily modified for Oblivion first and Fallout 3 after, at a certain point there was just so little original called that they called it with another name. Gamebryo's original company has folded anyway.
@mkreku: The engine can't even handle global dynamic lighting and day-night cycles. It's simply not suited to the type of games Bethesda games. As for RAGE itself, it's my understanding that it's not an open world game, although it will feature vast areas, but I can't find much info right now (nor I have time for an in-depth search) so take it with a grain of salt.