I genuinely believe that with a better balanced side, with effective players in positions we are currently shoehorning unsuitable players, we will see a more effective attack.
Do I think Hojlund and Zirkzee are good enough to challenge at the top? I'm not so sure - I'd be concerned at the technical ability of either, but I did see more glimpses of potential in Hojlund last year than we have this. I don't think either are as bad as it looks right now, but eventually yes - both may need to be replaced. I'd leave that until we see a side that is creating buckets of chances that aren't being converted rather than spending a fortune on a shiny new striker who is going to struggle with the same issues at the head of a dysfunctional team.
I also know the attack was the last piece of the puzzle to click for Amorim at Sporting. This season was always going to be a write off for him, with a mess of a squad and no money to address things in January, along with a hectic schedule that prevented him from seeing time with his squad to bed in new ideas, but we have slowly seen improvements in defence and midfield. I trust that attacking improvements will come in time too and I'm happy to be patient for that.