But Robert had an elder brother, Henry, who lived as a cleric. How Henry give up his vows and become king or Robert would be the new monarch?
Also, in case Eleanor doesn't die, could she push her daughter Marie as queen of France? And in this case, would she still marry Henry Plantagenet or would there be other candidate more interesting to defend the rights of her daughter?
I'd say all three possibilities are possible, given that french laws are not yet very firm and there is really no precedent for this, at least under capetian reign by that time.
So I guess the decision will be made depending on the personalities of each character and who can get the most support from the most powerfull nobles.
In that game, I's say Alienor has has some advantages as she IS one of the most powerful noble of France in her own right and her character being what it is. However, I think she will need allies if she is to get her daughter on the throne of France. One of the most telling card she has, I think, is the hand of her daughter. So, IMO, there's a good chance to have Marie as Queen with Alienor as head of the regency concil, but the price is going to be Marie maried ( in her cradle, nearly ) to the son ( or grandson ) of another powerful french noble. The English are out, I think, as Alienor will want a husband who will support her daughter, not overshade her. In my opinion, it will be either Toulouse, Champagne, Flander or Burgundy, with Flander being the best option in my opinion ( due to geographic position and wealth ). It just happens that Thierry d'Alsace, Count of Flander, has a son and heir, Philippe, about the right age.
So, we could get Marie, Queen of France, raised by Alienor, with her husband Philippe ( both raised together to ensure they will get accustomed to the wedding ). The royal domain which will be inherited by any progeniture will include Flander, Guyenne, Poitou, Ile de France as well as a few other land... Basically a big, nearly-continuous band from the North est to the South west of the Kingdom of France, and with some of the richest lands....
Any rebellious vassal will have to think twice, even the king of England.
PS : Susano, I still habe a few questions on that discussion, but rather that pollute this thread further, I'll send them by PM.
EDIT : As a second choice, I would say Marie OTL husband, Henry of Champagne, with the wedding taking place earlier than OTL. Then Hugues of Burgundy, but he's younger than Marie, so I'm not sure he will be a strong candidate. Toulouse just has a new count, but he is minor, so he may not be a strong contender and may be bought out cheaper, maybe by Alienor abandonning her claims to the county of Toulouse if the Regents for Toulouse support her daughter. ( beside Guyenne plus Toulouse runs the risks of francturing the kingdom between North and South; which is why I think Flander or Champagne are better )