So they survived the division, their ruler survived the siege where he died ( too lazy to google, wiki or whatnot ). What is her prime enemy from then on; is it still France or she sticks to HRE states ?
They would, with given time form Lotharingia again but the decision of that proportions would inevitably lead to non stop rounds of war with mentioned parties, or...? Would their power base remain in the burgundian part of modern France or gravitate towards Benelux ? For me only possible part of reality that would be true would be friendship with England and Spain in anti - French alliances, you ?