I think its incredibly foolish and na´ve for anyone to suggest Madonna is over and wont have another top 5 hit. Its going to be difficult but not totally out of reach. Celine proved with the fact song you can chart high despite being over 40. Give Me All Your Lovin' would have charted top 10 had it not been discounted because of the album deal.
If there is one thing people should know about Madonna its to never write her off. She has had more comebacks than any of her contemporaries and there is nothing to suggest this won't happen again. When American Life bombed she regrouped and produced Confessions which is one of the biggest selling albums of her career and Hung Up is her 3rd most successful single to date. She is Madonna and above all else when she dies all her songs will double in sales for pure nostalgia.