I think Starmer will win too.
He won't win a GE though because he won't purge the party of the people the electorate deem to be poisonous (Corbyn, Abbott, McDonnell, Burgon and so many others) and I don't think voters will forget that there is still a dangerous sect among the Labour MPs with anti-British values.
That same sect will then blame the fact that Starmer was a Remainer in 2019 as the reason for their defeat in 2024 despite the fact that Labour retained a lot of remain seats due to their Brexit position and Brexit wasn't the main factor for why Labour were crucified. That beats taking a look in the mirror at themselves and some of their policies and positions, and seeing how unpopular they were.
Which is exactly why they so rabidly go after the media and now even the pollsters in their own party because it's so much easier to shoot the messenger than to blame themselves.