Interesting thought, herindoors.
However, I think Helen and Lorraine get on really well, so I don't think Lorraine feels threatened by her. Also, I don't think Helen has had enough TV experience to take over the main role in the programme.
As far as I can see, the main problem is that the format of the show was changed, and the time available cut to only an hour. They simply don't have enough time now to spend a decent amount of time on any of the items. Plus, as we know, once Helen starts talking about beauty products, she just forgets to stop!