The idea that we can't sign a proper backup is ridiculous. United, Liverpool and Arsenal all manage to keep their forwards happy. Even Chelsea have Giroud and (for now) Morata.
Top teams have depth in every position. Sure, the best forwards in the world wouldn't be prepared to be back up for Kane. But there must be literally hundreds of younger forwards who can play up front or as an inside forward who'd jump at the chance to learn from Kane and Poch.
Keep their forwards happy?!.....
United have currently got £450k per week of strikers on the bench.
Arsenal have got 2 strikers. One of them visibly gets the hump when he’s taken off.
Liverpool get away with keeping Sturridge happy because he’s made of glass & knows he cannot be a regular.
We use Son as back-up and we have an experienced Spanish international also.