I don't think there's a setting to do it out-of-the-box, but you could implement it yourself. The media paths are created by an implementation of the IMediaPathScheme interface. By default, Umbraco 8 uses UniqueMediaPathScheme, but it also includes OriginalMediaPathScheme which generates the old numeric folder names.

You could enable the original scheme with a UserComposer like

public class MyComposer : IUserComposer
{
    public void Compose(Composition composition)
    {
        composition.RegisterUnique<IMediaPathScheme, OriginalMediaPathScheme>();
    }
}

However, that would use numeric paths for all new media items as well as preserving existing paths. If you want to use GUID-based paths for new media items, you could register your own custom implementation of IMediaPathScheme, combining OriginalMediaPathScheme's check of the previous URL with UniqueMediaPathScheme's approach to creating new paths.