Having a great deal of influence over both of her children (who both have immense political power), as well as being loved by just about everyone in the empire, what are the chances that she somehow attains control over more or less the entire empire? Sure, she said she was not interested in politics anymore. However, she has met all the Septim Emporers, helped ending the Simulacrum and had centuries of experience in ruling countries, as well as insight into imperial affairs.
Even if she does not become the ruler of the new empire do you think she will use her immense influence to lead things the way she wants them? As far as I understand Helseth wants to re-gain Morrowind's independence, which Barenziah might very well be able to help with.
Sorry for my rather poor English, it's not my native language. Thanks for any input.