According to Sanders (EDIT: actually Saunders), English lost 85% of its Germanic vocabulary after the Old English era. This is due to it borrowing foreign words, rather than continuing to add compounds and affixes to original words, German style. He also cites a sort of alternate history style list of words-'what might have been' if English had still used the old method. (e.g. aeroplane= 'flything'.)
So, AH dot com: how will Old English continue to predominately use the Germanic method, rather than predominately getting loan words? And what sort of language would emerge?