I think that depends on the leader. Tony Blair got a landslide, in part due to his image as someone young, vibrant, and cool. Remember all the stars of the day lining up to go to parties at 10 Downing Street? Remember him playing guitar with Noel Gallagher? Remember it all being part of "cool Britannia"?
I think people are staying away from Labour for a few reasons, chiefly - distrust of Corbyn and his competence, the sense of extreme division within the party, the focus on Antisemitism within the party, and the successful painting of policies that most people agree with as being extreme.
I think a new leader who came across as dynamic and competent could mitigate every single one of those. Corbyn, obviously, because he would no longer be leader, they could be seen to unite the party behind them, they could paint the Antisemitism as being due to Corbyn and something that they've dealt with, and I think that the last point would sort itself out largely on its own if the leader were someone that people could believe in because they already agree with the policies and because they'd want to believe in the leader.
The country's a mess and people are in a bad way. There's two ways to leverage that to gain power. The first is what the Brexiteers are doing - playing on people's fears by blaming an external "other" that will be excluded by the party policy (in this case, taking back our green and pleasant land from those filthy foreigners). The second is to paint the woes as due to the policies of everybody before you, and promise that you know how to make it better.
Both can work, but the latter requires someone with a force of personality Corbyn doesn't have, and someone without Corbyn's baggage.
If the Labour party could find someone like that, they'd be quids in, I think. Not going to happen for a few reasons, but that'd be the way to sell Labour policy to the public and get them on side.