I think there's an argument for Shearer over Kane, mainly based around how good Shearer was before his ankle ligament injury in 1997. Before then, 137 goals in 169 games in the PL is better than almost anyone.
But Haaland is in that almost anyone category. At present he's up there with Ronaldo and Messi in terms of truly ridiculous goalscoring. There's still a long way to go, and I'd be surprised if he stays in England for the rest of his career. Maybe City can keep him there financially, but in a purely football sense he might fancy a stint at Real Madrid/Barcelona at some point.
If he does stay in the PL it looks a done deal he'll go past Shearer at this point.